You could say that about literally any shady business. Imagine seeing a PDF proving tobacco leaders knew for decades that it caused cancer and saying what you did.
Being monetarily successful does not mean you’re good or shouldn’t be criticised.
Regarding sources: if you're genuinely interested and not just being argumentative for argument's sake, you're capable of googling "MrBeast geneva convention" and following the sources from there.
What specific acts are we talking about? "violation of the geneva convention" could mean literally anything between "putting red cross symbols on soldiers" and "summarily executing civilians", so it doesn't really narrow things down. If they're being put in uncomfortable positions, but they're not risking long term harm and it's voluntary, I don't see what the issue is.