would the casiino pay him or find excuse not to pay and ban his account?
Why not? If they are profitable already and can able to pay huge amount for sure they can pay those bettors if they win on their bets. Also make sure that you bet with clean hands because if you do something wrong which is against to their rules then provably you might encounter an issue with them.
Also so far Duelbits is doing good and there's no red flags to them at the moment.