I have come to understand that having a negative impact on people close to you or your family could be a sign of compulsive gambling, to the extent that this boy start maltreating his junior ones, I mean inflicting pains on them.
It could be, but I don't believe it is. Having a bad mind or not having any sign of sympathy for your loved ones and family members up to the extent of maltreating them is inhuman, and that's not a problem caused by gambling; it's a personal disease that the person needs to work on himself in order to get those rides out of him.
I know the disappointment that always comes when someone loses a game and the anger that will be attached to it because no one will feel happy about losing money, but that one alone does not warrant maltreating someone who has nothing to do with the game you lose. Most times, our relatives are supposed to be the ones whom we look up to, and we use their expressions to chear ourselves up instead of turning them to our punishment receiver.
Even if the said person has been stopped from gambling and no longer has access to gambling, there is still no guarantee that they will stop that reckless behaviour; it's inbuilt in them, and they need to work on it. Even if they are chasing a different carrier, any small thing that will provoke their anger can still bring back that beast in them.