If that person spends his time and all his money on gambling, it will not be easy to advice him to leave gambling. He will deny the suggestion because he thinks that he is okay and does not have a problem at all. He can not realize what happened to him because his focus is only on playing gambling. Many people can not manage gambling and even use it to make money which is wrong. That will just make them become addicted to gambling but they don't realize it. Someone who is addicted to gambling will difficult to stop gambling if he doesn't have a strong mind to really stop gambling.
If that's the case, I believe the person is indeed seriously addicted to gambling. They may feel fine even though they're actually experiencing financial difficulties, much of which they've lost to gambling. Furthermore, people who are addicted to gambling tend to be more stubborn. They may know they're being manipulated by the casino, but the desire to win big is what drives them to continue gambling without hesitation. Many gamblers end up with tragic outcomes, so only a small percentage of addicts successfully recover.