They're a tip jar and not a substitute for crowdfunding and/or setting prices for your work.
Discussion
sometimes it feels as if it's the main attraction for nostr, but that doesn't fix the underlying issues (which you often highlight).
It's not the main attraction of nostr.
Probably actually make more money crowdfunding to people spending fiat, since fiat is less painful to spend. But then your product or service needs more universal appeal.