There have certainly been cases where people have used casinos (and even exchanges) to hide/shuffle the origin of funds, 'cause when you deposit crypto on a platform, your link to the platform's address ends and when you go to withdraw, you withdraw funds from different origin (from other customers). Unless the platform keeps deposit/withdrawal logs of all user operations and provides them to authorities when requested.
This can be done even by people who have no intention of doing so. But that's the nature of cryptocurrencies, so like it or not, it's difficult for authorities to track the funds (even if the person isn't doing anything outside of their country's tax laws).
Yes, this could indeed become a problem in the future. Personally, I do not hide cryptocurrency and there is no point in hiding. But there are probably people who can make their money legally through these schemes. I think that the law (regardless of which state) will constantly regulate these rules and try to close these holes. This is why every year it becomes more and more difficult to play online casinos and gambling.