you have done your best for him, but he doesn't listen to you, he can't forget his defeat and tries to take revenge, and that will bring him down into misery, we can't act with things like this only his own self-awareness can change it
Its more better sometimes to let go than chasing after losses, we are instead going to keep on falling for the same mistakes over time, we are to gamble and never feels bad on what it could have caused us financially because it's not a means of making money, instead we needed that money to be able to enjoy gambling, we should deal with our addiction while it's still at the earlier stage than when things already got out of hands.