If someone wants to pay you 10 grand that's his decision. I don't ask for a credit report before I take money from a customer either, so for all I know I've taken money from people who couldn't afford it. I don't think it's your job to predicate every transaction on your customer's financial/emotional health.

However, I do think the closest moral analog to running a casual Farmville type game is running a casino. If you're fine with running a casino, I'm not trying to stop you.