Gambling is a terrible way to launder money unless you are willing to accept unfavorable exchange rates.
lol
Granted, when you are not gambling large amounts infrequently, but rather in small increments frequently over time, the loses are reduced to an increasingly predictable percentage. However, those loses are built into the system. The house always wins on the whole.
Over time the guy is probably losing. But what if he amasses 1 million dollars illegally annually. You launder through your gambling. The guy takes home 90 cents on the dollar. Why would the casinos comp this guy if he constantly won money from them?