One thing we need to keep in mind is that the children of today will determine the future of tomorrow. So we as Guardians cannot do anything that endangers our future generations. As guardians we must try to fulfill all the responsibilities we have. Unnecessarily they cannot do any criminal or prohibited activities in front of them. When family members participate in gambling in front of a child, they tend to focus on those forbidden activities and show self-control. If a child sees family members, it will definitely matter and will become a gambler unconsciously. Therefore, as much as possible, we should avoid gambling, drug addicts, violence, and other social crimes in front of children.
If every parent wishes only good for his kid, only bright and positive future, and that has been for centuries, then how come we have bad people? At what point that "bad" sneaks between overprotection and total monitoring? Where is that moment when parenting fails?
Btw, despite gambling, parents do all kind of activities that are inappropriate for underaged. Do you think kids really focus on all of them? Example. We dont let kids use sharp objects like knifes or scissors. The damage they can do with it is immediate (not just a possibility like gambling addiction). However they see us using them, but they dont focus on them, nor show a huge passion to use them. Moreover, if a kid is a girl, we even push or ask her to help to cook, to slice something and etc. We even teach them to use it when they are very young and give them toy kitchen as a toy to play with plastic knifes and etc. Then where is logic here? From very young age we teach them to use dangerous objects.