Well, it's probably the same as it is with other things like Onlyfans: People see other people be successful, think it's easy and try it themselves, but they don't see the kind of work that goes into it: First to build a fanbase and earn the trust to get big and then maintain the quality that got you where you are now, if you even make it this far.
There are some pretty big fish from what I've seen, like 20k+ per month big, but most of them are probably low to mid 3 figures which isn't enough to live off of in many countries, so they give up on it or change course so much that the foundation of their "success" breaks away, like let patrons decide how the story goes or introduce something stupid.
Back when Big Brother was still a thing we had Eric as a major roadblock that could be kept in check with the right tools, but at least one other game decided to introduce something similar and it completely backfired, because
1) the fanbase didn't want it and
2) it was implemeted poorly.
Absolutely. I think what we're seeing is more or less a consequence of market saturation. It's something that happens in pretty much every modern social media / influencer space that promise financial gains: YouTube, Instagram, Tiktok, Onlyfans, Patreon and the like. And unfortunately, the indie space follows the same rules.
It usually starts with a few individuals who gain a large following, and presumably equally large earnings; soon, other people decide to do the same, hoping to achieve the same fame and following. But they soon find that once the market settles, they hit two walls: first, the money circulating does not grow per se, but is simply divided among all the creators, so the addition of more creators simply means that each creator earns less on average - a.k.a, opening a new pub in a street full of pubs. Second, adding new voices to the same market means adding background white noise, and it also makes it harder for newcomers to stand out - or as Ben "Yahtzee" Croshaw said, it's like throwing a message in a bottle into a sea of messages in a bottle.
Unfortunately, it's a fish-eats-fish proposition, and it incentivizes creators to seek the largest common denominator to maximize profits. This also leads to the blandest creations possible, and high abandonment rates as was said. As for me, I usually look for the few passion projects, led by creators that care less about the profits and more about telling the story they really want to. This means wading through a lot of cruft, and possibly not noticing hidden pearls; but I think that's inevitable when you have a limited amount of time to dedicate to an hobby.