I'm putting in my blunt honest 2 cents to this topic
The reason I would pay to support a comic would be the same as the reason I would pay to buy a music CD (even though it has been bootlegged on youtube), or a BluRay (of something you can download in HD off torrent), or a physical or even digital book (that has been bootlegged all over the internet):
It is because they are great, I love them, they add value to my life and I have the money to spend to support them.
However, my standard on spending on entertainment product, which can be considered as tertiary needs, needs that you can live without, is pretty high.
The music CDs I bought is not being recorded inside someone else's garage, they're professionally done.
The Blu-ray is also not recorded by a handheld smartphone, and the printed physical book or even the digital ones should have a standard of professionality to them, imo.
I believe the reason alot of webcomic is having a hard time getting these income is because alot of them, at least the ones I've seen so far, seems far off from the professional standard that anyone would pay money for.
To add to that, alot of them are done as a hobby on the side, with no ends in sight, no guarantee it will be finished, and I personally would not want to read, or let alone pay, for something that has a high chance of being abandoned halfway.
You have less chance of that risk when you put your money to a comic published by a publisher, whether its printed or digital, because the publisher's job is to make sure the artist finish them, unless an unforeseen circumstances prevent them to do so.
For these kinds of products (yes, webcomic is a product whether you want it to be or not), I'm more inclined to give into a tip jar.
Monthly gift seems too much of a commitment, unless the comic quality blow my mind at first sight, and I want to see awesome behind the scenes stuff of how to do it.
I don't think it's douchey at all to put reward behind a paywall, cos making those tutorials and edit them cost time, and I personally think that time is more valuable than money,
Time is a non renewable resources that the artist better spent on finishing their comic than teaching random people on the internet how to draw.
So if those random people on the internet wanna learn how that particular artist draw, well they'd better open up their wallet, otherwise go look for free speedpaint on youtube, there's plenty of them out there.
I think it's fair to ask for money for something that add values to the person who's asking.
I have opened up my wallet to only two free webcomics so far that blew my mind on first sight, and I think it was worth my money, because they meet the standard I set for buying anything that classified as tertiary need, which is entertainment.
as far as adverts, I use adblock, and there's a valid reason why I did it
even though it does not cost me money, these ads can be very intrusive and sometimes opened up pop up and try to install some stupid app on my phone, that's why I hate them.
I personally would rather pay netflix style subscription for good procured content of webcomic, than reading it for free and have stupid apps popping up and try to install shit on my phone.
As far as people who expects webcomic to be free, those people are the kind of people who probably would not pay for entertainment anyhow, so the goal is not trying to convert those people,
but to make something worth it for the people who do pay for entertainment to want to pay for it.
It is possible that the people who always expect things to be free are not in the position to have extra cash to pay for entertainment.