Advices won't work to those gamblers that are addicted already. It's difficult to cure addiction and simple advices can not even help a little. Gambling addicts need to shift their attention into other things and they need a family care for recovery. That's why it's very hard to be atrached on something that will destroy your life.
They need to be willing to help themselves.
Doing such help even with their family will only help if they start helping themselves. The habit can't be removed easily but with their own help to themselves, the cure will make it easy for them to moderate it.