As almost every casino has KYC system where kyc is required when someone invests huge money or wins huge amount. In that case I don't think a crypto casino can be a big cause of money laundering. Because if someone is doing money laundering there then his identity will be revealed due to KYC so I don't think anyone will choose crypto casino as a money laundering route.
There are so many ways to launder money, not only in a casino. A wise criminal will find the best way. Those who use a casino are I think have another purpose other than to launder money. Maybe they literally want to play a gambling? To have fun or to possibly increase the money that they deposit.
There are gambling sites which doesn't mandate a KYC and if the site blocks them upon withdrawal asking them to upload their KYC, I think they will use someone else identity. There are so many things that you can do if you have lots of money and you can easily get away with the crimes that you will be doing. This is the power of money.