People who are close to him should try and advise him to take the right steps and avoid gambling for the main time. Let it be that it's still part of the winning that was lost back to gambling before it gets to a point where he might end up borrowing just to fulfil his gambling desire.
Advising people involved in gambling is not easy because they have their own understanding in assessing gambling. But there is no harm in giving advice as long as they have a friendly or fraternal relationship. About taking out a loan to gamble is a big mistake and if he does that it means he is starting to get addicted to gambling.
That's what I've always said, It's quite hard to give an advice to other people especially to a gambler because gamblers have their own rules in life and even if we advice them what's good for them, they will not follow that because some gamblers is in the point of their life that the only thing they will do is to follow their own intrusive thoughts. When it comes to spending money, it's easy for a gambler to waste money on things that aren't that important because they already have it in their mind that the money they spend is something they can easily get because of gambling but of course we shouldn't have that mindset because it's not we always win, right?