If infrastructure is in place and minimal labor costs are involved, taking any percent, no matter how low, is sustainable.

Think of a bank. What % does a bank take of your money? like 1% on the transaction, right? And it makes money on that tiny percentage.

There's no reason OnlyFans needs to take more than 5%. It advertises itself, it's a meme at this point. So you need a handful of web devs, email tech support, and accountants aaand... That's it. Like a dozen employees. The website runs itself, the content is made by other people, the money is processed via third party, the advertising is free, the customer base is both captive and gullible, the ONLY way to lose money on this is to go woke.