because psychologists will only help your friend to be even more enthusiastic to be even better to avoid gambling. and I think a strong push that can make your friend change for the better is usually the closest person he loves, like his wife or girlfriend.
The encouragement of family and loved ones can also be a factor in the success of this change because a person can change his mindset and behavior when there is encouragement from people around him who love him.
But unfortunately, only a few people or families want to care about someone who has become a gambling addict.
but somehow the OP's efforts are really helping his friend or just choosing to be silent.
But if I understand cases of gambling addiction, it is indeed very difficult to cure and only certain people can completely recover from gambling addiction.
I myself am not sure that a friend of OP can recover completely, maybe he can stop gambling for a while but there is still a possibility that in the future he will return to gambling again.