you have an MVP that sounds like you've actually honored the "M" part (as many fail to). You find it useful already. Do you honestly think you won't be able to get $500 worth of customers? If you really think that, then just stop. It's not worth your time, because $500 worth of customers is nothing. I'm assuming you're charging more than $1.

If you can get more than $500 worth of customers then who cares? All businesses have costs. The question is, can you recoup them?

Yes, you can incorporate yourself online for like $150, and about an hour with google will tell you which form of corporation is the best fit for you. Probably S-Corp I'd bet. C-Corp is probably overkill.

BUT regardless of if you use that Stripe service or not, use their $500 barrier of entry as a guide for if it's worth continuing or not, because obviously it's enough to make you pause.

No one is suggesting that the business should be built on Paypal. We're talking about a phase where the company is trying to land its first 14 customers or so.