Let me tell you how, you buy crypto with your dirty money^[1], you can use a mule or smurf to split the bulk amount of crypto that you've bought from your dirty money with and those smurfs will register on a casino and put their crypto in their and depending on your instruction, the smurfs can play a part of that crypto and then they withdraw that money or they can just withdraw it after depositing I'm not sure about this part though but I think that's the reason why casinos are restricting people from withdrawing without playing or withdrawing without a KYC and then they might also use some mixer to further muddle their tracks of the laundering and there you can enjoy your "clean" money. I think I'm wrong with my process but if anyone will correct me, feel free to do so.

^[1] You buy the crypto either with P2P online or physically, it depends on where the dirty money is but I believe that most of them do a P2P physically.