The confusion and contradiction is there, how can someone happily gambling can be said as bad? You're only going to harm your family if you are affecting your relationship to them and all of your obligations are being ignored.
As long as you are a responsible gambler, there is no problem for you to keep on going on. There are bad gamblers in real life and they are the ones that make gambling bad in the eyes of money like you OP.
And as we say about getting out of the kitchen when you can't take the heat, the game goes for people that can't take the effects of gambling for themselves.
I am rather inclined to believe English is not the first language of OP, so she/he has a little bit of trouble communicating what she/he actually means to.
Anyways, I mostly agree with you, one is not supposed to gamble if there is a precedent of abuse of the money and the resources which are not supposed to be used for leisure. Sadly, the history o my repeats when we talk about problem gambling and family, rarely ends well, unless the problem is treated in time and with the help of professionals or the support of the whole family.
Anyways, Does not matter who this person is or what caused his family to start to have those problems, I hope from the bottom of my soul things improve for them... I cannot imagine the pain one must suffer from having a family broken by gambling problems.