What could happen in extremely rare cases is that a whale gets lucky and sends a casino into bankruptcy. However, I would not have come across such a case yet and you would probably actually need someone with a lot of Bitcoins ... and a lot of luck.
I don't think so that's how casino business works as they have house edge and also liquidity with them to pay off any win and going bankrupt means they should not have entered in this stream first of all because you estimate every aspect before registering any casino.