we prevent people from gambling on early stage startups and risky investments by limiting investment to "accredited investors". same thing should apply to gambling.

I believe some countries/casinos in Southeast Asia have policies that you either have to show a foreign passport, or put a deposit of $500-1000 down to enter the casino, that you get back when you leave, with the theory (easily exploitable, I'm sure) being that you can't leave the casino penniless.