Although the casino can detected that, those gamblers will not stop for trying to do the same thing. Maybe they will try in the other casinos that they don't use before so they think that they will have the chance to pass the blocked.
You nailed it! Or maybe they stick to the same casino but use a different identity, device, and IP address. These gamblers are clever, they always have a backup plan in case something goes wrong. And these gamblers won't stop as long as there are people that are willing to supply them with the documents they need, because its just like a supply and demand thing.
However, in terms of risk, its not on the casino because as long as the gamblers are losing, they're welcome all the time.