Show me someone who's run into a depressed rut over not enough having subs because they feel they're "not skilled enough" and I'll show you 10 who got into a depressed rut over not having enough subs because they feel they're "not marketing enough". You're conflating a symptom for a cause. People grow destructive behaviours on both ends because they don't understand how to separate their work's performance from their self perceived inherent worth as a person.
Ever watched a show like Dragon's Den? You have a handful of millionaires+ who're looking to invest in the next best hit. Everyone thinks they have the million dollar idea, but only one or two can actually prove their product's worth to the investors. It's not that they're charismatic speakers, it's that they knew how to craft something legitimately worthwhile that either;
A: Solved a problem
or
B: Innovated an existing concept
or
C: (Both)
The reason I make this analogy is thus. For one, making comics with the intention for success can draw a lot of lessons from this, when considering for the marketing angle. Is the plot simply just genre over-saturation? Does it follow the already composed orchestra note for note, not offering any difference to the same tune listeners have heard before? If not, then on the face of it it can't really be marketed unless it's been crafted by the gods themselves. You've left yourself in a position where you must compete on a skill set basis. Have fun.
Does it solve a problem (niche?) There's a popular one being touted that almost every indie creator is jumping at the bit to fill these days so they might conquer the current zeitgeist, and yet we're already witnessing the mumbling and groaning from audiences who're long done with it. If the aim is truly 'make a marketable' story, research is in order before the plot can even be crafted. It can't be treated as a mere hobby and then have unrealistic expectations slapped upon it after the fact. What truly sets this story apart? If you insist that skill isn't any basis for success, then you need to be a very creative thinker in order to make one in a million success like One Punch Man which got sold entirely on it's brilliant writing. You're deliberately shooting yourself in the foot by denying yourself one of the most fundamental bases on which to set yourself apart. Being good at what you do.
Are you honestly going to sit there and tell people they need to keep hoping and dreaming they might one day strike lottery levels of luck with their series if they just keep trying to market something with obvious honest to god flaws? Really, this is the healthy approach for someone who is depressed? How about something that is within their control. Something that they can daily apply themselves to and journey towards self growth with. A little something known as persistence, practice and patience. Learning to let go of unhealthy habits, learning to not perceive your worth as numbers and learning that this ill perceived notion of "making it big" is not required to call yourself a comic artist. It's alright to want the numbers, it's why people create. So they can share.
What's not cool is knowingly sending people down a spirialling path of self loathing instead of pointing them towards something that they can actively work on and see immediate results. If "numbers are weird and come from all over the place", how about we stop telling people they need to rely on something so random for the mere chance that they might find fulfillment through them.