On the one hand, if an addicted gambler won a large prize, there is a good chance that he will soon drain it back, and at the same time, the entire deposit.
Indeed. I even doubt that addicted gamblers can enjoy the prize even if they win a large prize. They probably will dream to win again and again bigger prizes. So, they may have no idea to stop temporarily enjoying the prize. True, they easily drain it again soon since they are trying chasing more wins. For me, enjoying the prize is a must. It can make us more comfortable and it can be a good booster of our mood.
But on the other hand, casinos really should be interested in preventing gamblers from becoming addicted because such gamblers won't be able to bring profits for a casino in the long term.
TBH I won't blame them, it is their money. But this addiction probably makes them to have a very short time in gambling. When their family knows their addiction problem, he must be ordered to stop permanently. Addicts also have no idea about managing their funds properly. So, they must have a problem with their financial in the long run. Once they have the financial problem, they no longer can gamble at all.