Hoping that the person will listen and follow whatever they've observe that's needed to be change, those close people that's sorround the person will be an additional key not to fall into addiction, just need to take the advise as positive criticizm and help himself to adjust or quit away if it's needed.
Acceptance of other people's advice from gamblers also depends on the personality of the gambling addict himself. Some people are easy to approach or conversely, some people find it very difficult to accept advice from other people, even those closest to them.
I see that some gambling addicts are difficult to advise. Telling them about their outrageous activities in gambling will only fuel the fire of quarrels. sometimes we just need to pay attention to them and approach them when they need advice.