Alot of money laundering was done by most of those high drug orders through casinos and that was why the idea of kyc came into stand and when the kyc policy wasn't covering enough, the wagering requirements was then introduced and I believed that this two principles has truly helped to reduce the rate of money laundering through casinos because most casino will need you to wager the equivalent of your deposit amount before being able to withdraw your deposit and you'll agree with me that its not always easy to wager and come out successfully.
Casinos on their current form were born on the US and at the time the Italian mafia used them to launder their money and to obtain even more profits, as such gambling has always had the attention of the US and many different governments as they know that if the regulation is lax then some illegal activities can occur.
And while most cryptocurrency casinos themselves do not engage in any illegal act, those that use them can be a different story as they could try to launder their money in this way, and as such casinos will eventually ask anyone that makes a big deposit to identify themselves so they can remain out of trouble with the law enforcing agencies.