This may have worked for your neighbors whom you did advised but isn't a guarantee that it's going to play out same way for another, you have to understand that there are different levels of addiction and so they also demand different types and levels of elimination so the remedy will be different but a professional help has been proven over time to have worked so well that many gamblers have been able to scale through gambling addiction and turned a new leave after, so it's become a well pronounced and recognized.
That's right, sometimes just a piece of advice won't affect those who are already addicted to gambling, someone who is already addicted to gambling will not be easily influenced by just a piece of advice, they might listen but it only goes in one ear and out the other, like the saying goes, this is what happens to them, even though they listen to the advice given by others, they won't listen to it properly.
In addition, with different levels of addiction as you said, it is true that not everyone who is addicted will recover with just a piece of advice. Maybe this advice will work for those whose addiction is not very severe, but for those who are severe, advice alone will not be enough.