I read more about Cohost's situation as of late, mainly from Lori's website and fedi blog, and it really shows that Cohost's downfall is mainly due to poor management and business decisions.
Poor management in the sense that they were very inconsistent with finance updates and not getting features out on a timely manor. There was a 6 month gap of no finance updates, and were there was one, it was simply blamed on ADHD. Features were also taking a long time to come out, some taking attention from other features people were wanting. I understand that coding can be difficult and there can be unexpected hardships along the way that can eat up a lotta time, thus needing to delay the feature. But this was a constant issue, not something that happened from time to time. It didn't seem like there was a plan in what to implement first either, as well as leaving other stuff behind like never updating the promo image for what a cohost+ subscription provides despite adding more benefits down the line.
Which leads into bad business decisions, as Cohost didn't really have any way to make a profit outside of merch and cohost+ subscriptions for a majority of the time it was running. The tipping service should have came out once or shortly after Cohost opened to the public, but it never came out. Artist Alley could have been a lot more, something like Tumblr's blaze system or side banner ads like mspaintadventures pre-VIZ buyout, providing an advertising method that was not intrusive and helped users get attention rather than keeping big corp/product names relevant. But once people realized Artist Alley was just a whole separate page most people wouldn't bother looking at, most users pulled out. Running a small niche website that doesn't have a good way of making profit while also trying to pay each staff member $94k per year is not sustainable either. I understand wanting to pay everyone fairly, but that doesn't work out when you're small and struggling to make money while continuing to record losses, especially if the founders are also paying themselves that kinda money.
The final nail in the coffin is likely the cancelation of Eggbux, but it isn't because of Stripe. Stripe's policy changes didn't kill Eggbux, it was the negligence of the staff not reading Stripe's policy at all. Stripe never allowed the type of tipping that Cohost was wanting to implement. The reason why Eggbux was canceled in May 2024 and not the very early days of Cohost was likely because Stripe sent out an email about updating their policy changes, which included a change to "content related tips and gifts." However only the wording was changed to make it more clear, and nothing about the policy it self was changed. This either means Cohost staff never did research into if Stripe would allow their Eggbux service under their policies, or staff thought they would have been in the clear while developing it, but the updated wording on May 2024 realized they weren't an exception. This really puts into question if Cohost was really working on Eggbux all this time.
There's a lot more that I can go into such as the moderation issues, the fact they lied about being non-profit, and how some staff members likely had friends that were effecting their decisions on banning loli/cub off the site, but you can learn more about that on Lori's blog and likely other posts (I honestly haven't searched on cohost today.) The main point is that cohost could have been sustainable, but the decisions the staff made effectively ended that possibility. There is a market and interest in what cohost was providing and promising, but it has to come from a start-up that knows what they are doing and plan ahead accordingly.