Good point.
I think LoyceV's explanation of this is more plausible. The vast majority of crypto casinos, at least the ones that advertise on the forum have a license from a tax haven, typically Curacao, and some are not even licensed. Gradually they have been implementing more KYC/AML measures, at least in their ToS, but I think this is more to save face than anything else. I say this, because for example I have read the ToS of a casino in which I deposited and bet, that said they required KYC for if you have in the account more than $2k or total movements for more than $2k but then they allow you to create an anonymous account and bet whole bitcoins. At that same casino, someone closely associated with it confirmed to me by PM that he had not seen a single instance of KYC in several years. And that casino is no exception.
After your comments in the thread, it is clear to me that I will first withdraw to my wallet and then pay the prize. But about this I want to say that I have cashed out from several casinos in signature campaigns and I have also deposited and withdrawn in some of them, I have never had any problem in spending those funds. I'm not saying that it can't happen in the future, and I have never thought of putting them in Coinbase or similar site.