Once a gambler breaks that taboo and they begin to borrow money to gamble there are very small possibilities of succeeding on making them see how mistaken they are to do this.
As it is obvious that at that time they have lost any kind of common sense and they are willing to do anything to fuel their addiction, this is also the stage in which even their loved ones and friends distance themselves from them, as once they owe them money, money they know they will never recover, they become unwilling to keep helping that person to destroy their life by financing their addiction.
That is not going to help the victim; in fact, I think that's when their loved ones should stay by their side to let them understand that what they are trying to fully involve themselves in would have a bad side effect in their future, unless their relatives are really feeling less concerned about the victim's well-being. Some of those gamblers who borrow money might not take those loans from their relatives but from other friends or fellow gamblers. Some of them, after taking those loans, don't bother to repay until it begins to cause issues; that's when the report will go to their parents or relatives, and they will be the ones to cover the debt if they have a good heart. If you see any of your relatives going down that road, it's up to you to start correcting the person.
This is the reason that I have always said that the best way to cure a gambling addict is when the person realise that they are very much addicted and the person involved who is the victim understands that they need help. That is the fastest way to rescue someone who is addicted. If someone is truly addicted, but they do not understand that they are addicted, all the effort you put in stopping the addiction will result to nothing. Thereby rendering their efforts fruitless. That is why it is fine to first convince someone that they need help before rendering help to them.