Building off of idle compute

Few similar projects out there, but would love some advice. Would be creating a project to monetize idle computing power - first with crypto mining then eventually some sort of AI training/generation. Could also add bandwidth sharing to make my own proxy pool or get paid per user.

Assuming I need to maintain a .25/user cost basis; how would you approach advertising? US based PC users would be the target market.

Yeah you could run some hosted LLM's if you need it but it all depends on what you'll actually use