Personality can only be changed if the person in questions morals character is questionable. This is because if you are a discipling person no matter what comes your way money can't and should not change who you are.
This is the reason it is banned in many Muslim countries and few others. This is something that the state does not allow you because after you loose all your money in gambling, you have nothing left and there comes the responsibility of the state to fund you. So according to the paternity law, the state has the right to enforce the regulations upon you.
Banning gambling is not completely effective after the introduction of online gambling. This is the reason why crime rate and addiction rates are keeping increasing in most countries. Young generations are seeming highly irresponsible about their duties and everything whereas governments also helpless in this regard. Only spreading awareness against gambling alone may bring changes to those young generations.