In my experience, yes you are wrong.
Majority of my readers are not creators, or if they are, it's not a primary goal for them and they just write fanfiction for fun or something.
I think 1/3 of my subs are other creators who I've friended on the forums and the rest are just random readers(maybe creators? I honestly have no idea cause I don't check all the profiles of everyone who subs me)
So I actually like to keep a look out for fellow creators subbing to my comic. I occasionally check my sub list because of it, and of those 3k subs the vast vast vast majority are not creators.
A good majority of readers are on the ap, which has no ovious link or prokotion to the forums that I’m aware of. The desktop is a mix but very much for creators as we use it to do all the uploading of our comics and stories, which is where you can find the forum link.
So I believe the forum is largely creators. Perhaps those comics that do a lot of promoting on the forums end up seeing a larger portion of creators in their subs. But it makes sense to me that creators would get more use out of the forum than readers. Reading can be a pretty singular experience unless you want recommendations, where as creators benefit a lot from communicating here about contests, strategies, critiques, and so on.
You’re wrong but it’s fun reading other people’s theiries! And it’s good to question the status quo. You never know what you’ll shake loose. 
I love your theories are very interesting! I think that the forum is formed mostly by creators because we are the ones really engaged in the platform and process, is very rare for a reader to do something more than...read 
most don't even comment or subscribe. I don't think most of them know that the forum exists!
I had been a reader for years and didn't even have an account until recently. There are definitely much more readers out there. With my experience as a "common" reader I can tell that comics that are not featured/premuim/picked by the staff are practically nonexisting. You CAN browse but you don't because you assume that the front page will have everything that is good in the platform. Also the app shows prominently specific content. Readers get overwhelmed by so many options and stay safe picking what is accesible.
Until I became a creator I was able to find hidden jewels because of the forums and profiles. Yes, if you are a small creator your subs will be other creators because they are the ones engaged enough to see you. I think creators are usually supportive, I haven't encountered mean ones. (Also because if they sabotage someone they might fear it will come back to bite their own comic in the ass XD). Sad but true, readers are less likely to find us because they don't usually browse, nor are willing to take the risk of losing time trying stuff that is not "pre-selected". I felt that way, many readers I have spoken to over 7 years say the same.
As punkarsenic mentioned, common readers consume what is easy to process. In no way I take the merit away from popular stuff, it is there for a reason, they work hard and deserve those views. My point is only that reders don't usually reach for anything else, of course there are exceptions. Perspective radically change when you become creator, doens't it? XD
I was going to post in your other thread that it's been my experience too. I have some dedicated fans but word-of-mouth just doesn't seem to happen online. Or at least it doesn't below a certain level.
I suspect it's like this for most free offerings on the Internet. The problem is not that we aren't able to find readers, but that we aren't able to convert them into active participants. They remain passive consumers of entertainment. And I can't really fault them for that. They didn't have to pay anything, so they don't feel invested that way. The content doesn't come out at a fixed time like a TV show, so there's no perceived opportunity cost either. There may not even be extensive archives to binge on and thus distinguish the dedicated from the dilettante.
There's also the Firefly Effect. You never know when a webcomic will go on hiatus so you hold yourself back from becoming a fan. But then too many people do that and the comic folds from a seeming lack of interest.
This idea has been brought up before on here -- I can see where the suspicion arises, especially when you look at the forums!
But as others have said, it doesn't hold up when you take any large comic and look at the profiles of their subs, and count how many of them have their own comic -- the vast majority don't. I used to give out thank-you notices on my subs' profiles, and a loooooot of my readers were people who looked like they'd just signed on through facebook to read comics and never bothered to do anything with their profile.
This is also pretty normal on the wider internet! Creators in years past scratched their heads over the popularity of comics like Ctrl+Alt+Delete and Dominic Deegan, while something beautifully drawn and poignant like The Locked Maze was never really noticed on that large a scale. It's why we say there's a healthy does of luck in this game -- getting an audience isn't something that automatically comes with quality.
While I have seen a competition mindset emerge on sites with subscribers, I don't think it's common. One of the big reasons I've always liked the webcomics community is that it ISN'T viewed as a competition -- I don't have to worry that if you read Joanne's webcomic you won't read mine; you can read both. And skilled creators tend to be the ones most vocally supporting other comics that they personally like.
You'd have to be really petty to go around liking episodes you don't really love and avoiding interacting in any way with the episodes of comics you genuinely enjoy. But more importantly..... why would those people interact most with comics that are already popular? If you're threatened by competition and feel like you can't get ahead because of other comics stealing your audience, why would you then strengthen the hold of the really popular people who are "stealing" your spot on the front page? Wouldn't you go find mediocre comics with 2 or 3 subs to aggressively support -- the sorts of people who will sub back to you and be more likely to read your comic in return out of gratitude, but don't threaten your ranking?
And that tends to be exactly the behaviour I see from the few folks who do fall into that Threatened Mindset. Those are the folks trying to get sub-for-sub and insisting that if they read your comic it's impolite for you to not also read theirs.
A trick to fight the firefly effect is to build up your reputation by being as consistent as possible. The key is to know how many updates you can consistently pull off considering your time. Last year i was able to update twice per week, but this year has been busier, so i had to reduce it to once per week for now. Also i have been consistent with my update day (save for two exceptions, one for a particularly busy week and another because it was my first digital page).
Another trick that may help when going to a hiatus is to give a returning date and keeping up with it. I had a hiatus in january. I told my readers about it and said i was gonna be back in march and i did it. This helped my readers to know i was not "dead" or something.
I feel the majority of people on Tapas are not creators. I sometimes take a look through my subscriber list out of curiosity and I always find that the vast majority of those people are not creators. Creators are definitely over-represented on the forums, because, as you said, a lot of use the forums to self-promote.
I feel this is because the "quality" of a comic does not necessarily translate to how enjoyable it is to people. For example, a lot of BL comics become very popular on Tapas even when they might not have the best art/writing around simply because there's a lot of readers out there who really love BL. On the other hand, a very well made and polished comic might have difficulty finding an audience because it's an unpopular genre.
Oh yeah!! I forgot to mention that! When you are a reader and the content is free you are not as invested, also because there is no formality that obligates the creator to go on. Just like you said.
I must say that having very devoted readers can be very positive to make the comic grow...but also this can backfire if the readers change from engaged---to--entitled!
Most readers are willing to wait during a hiatus, would forgive some mistakes, changes in the quality and if they don't like something they silently go away. Some people who are very active in a comic/project can become so demanding. If they don't like something they will try to destroy you because they feel you betray her emotional investment. o_o At certain point is good that many readers are reasonably engaged or even silent.
Dominic Deegan had a satisfying story though. Mookie partnered with an artist for Star Power so that strip has both good writing and art.
Sure, it makes a difference, but you gotta admit that every newborn webcomic has the life expectancy of a medieval baby.
I am the Tolkien of centaur erotica.
Including this topic? lol 
Silent Horror has 290,000 subs. If you look at the total number of comics and novels listed on the site, it's not more than 55,000. Taking into account that some creators have multiple series that's, what, 20% at most? And that's assuming every creator on tapas is subbed to Silent Horror. (is this how math works?? honestly I dunno but clearly there are more readers than creators).
A simpler theory: most Tapas users are on mobile, and one mobile 1) engagement on mobile is naturally very low, and 2) there isn't even a link to the forum. Even on Desktop the forum is listed under your profile in the menu, which a reader has no reason to even look at once they've finished creating their account the first time. So it makes sense that readers would have a hard time finding it at all.
Plus as someone pointed out in an earlier thread, readers don't need to come to the forum to talk about comics they like. They can do that in the comments of the comic itself, if they're inclined to comment at all.
Ditto on the whole "there are more readers than crestors" thing. Even on my comics with a smallish audience (almost 500 subs) the majority of my readers aren't creators. That said... The majority of my ACTIVE readers (the ones that leave comments and likes) are creators. Creators are the ones that understand how much comments and likes can mean to someone, and how much they impact your ability to reach trending.
You can call it cynical but I try to leave a like on every page I read (unless I really really hate it). This isn't me jockying support for the creators I associate with, it's just straight up the bare minimum I can do to support the creators I enjoy.
Sometimes I think I've ruined my chances of every getting an HBO series. But then I remember that Game of Thrones has loads of nudity and brother-sister incest.
In the beginning here my comic mostly got subscribers that had there own comics. Now I would say I am noticing an opposite trend. Almost all the subs I gotten recently has had nothing on their accounts except others they are following... So I think the numer of people who are "just" readers are growing. 
It would be interesting to see some stats on that tho. ^^
Creators are just overrepresented among the vocal readers.
Now, r/Fantasy4 probably is mostly frustrated fantasy writers.
I don't appreciate you insinuating that I am fishing for subscriptions. I am not. What I am in search for are honest conversations about fairness on these Webtoon hosting websites. The only reason I am here at this point is because of this forum, or that one-in-a-million shot at a feature.
I also grow tired of having to do things to get reciprocated attention, such as read everyone else's stuff, "like" everything, etc. I'm a creator. I work hard on top of a full time job. I do enough - I help tapas have more readership and ad revenue. We all do more than "enough". The hosts may consider that the massive majority of comics out there, that are quality, with 50-500 subs, when put together, vastly outnumber the few big ones that they constantly cater to.