Have you ever thought of donating the gambling profits to a charitable cause ? Sometime people won a big lottery or very high amount of money from betting & gambling games. Do you ever thought of being generous and helping the poor with this money ?
Personally I will not donate with the money won by gambling, making a donation with the winnings of gambling is not useful. there is one belief in my area that believes that feeding other people with dirty money will only make the recipient unlucky, and that myth continues to grow until now.
useful or not it depends because indeed some religions forbid it. but outside of that religion, maybe people have different views, no matter where the money comes from because helping a lot of people who really need it will make them happy because there is still concern among humans.