I don't totally agree with this. Gambling directly affects your mental health too. Do you know why people become a gambling addicts? This is because they play too much gambling that their mind fails to recognize how much gambling is good or bad for them. They are unable to make the right decisions and this is directly linked to mental health.
Also if people start to lose in gambling, they will become tense. They will have a very adverse and bad effect on their mind. Just like winning in gambling and getting a lot of money can have a good effect on the mind, losing money will have a bad effect on the mind.
The reason people become gambling addict is because they lose and they keep playing. If you lose a game there is the tendency that you want to go back chasing the money that you have lost and you find yourself always playing and like you said it gives a tense feeling and hatred, anger or envy may develop from this and this change the character and the way the person behave. You see a gambling also doing drugs because of such effect on their lives.