In my case it has not happened to me, but I only bet at reputable houses, I don't cheat and I usually read the ToS. I don't bet large amounts either, which I think helps. But I have seen a lot of people accusing the casino of not paying them, which in some cases ends up being revealed to the casino as a scam, and a typical one would be 1xBit, but in other cases the casino claims that the player broke the ToS, with multi-accounting or otherwise.
It has also become very fashionable, now that crypto casinos almost all carry KYC requirements in their ToS, not to apply KYC while the player loses, but if they win above a certain amount they are required to do so. And there are cases where they 'discover' at that moment, that the player had been playing from a country that is on the no-list and things like that.