Why does his family don't seek a professional to take care him? gambling addictions isn't a joke and only can be solved by prohibition.
Maybe his family didn't know that he often gambled, so his family didn't look for a professional. We also will not know what happened and how his relationship with his family.
You wouldn't know what they're doing with your money and it's dumb if they tell you if your money used for gambling, the best way is don't lend your money to anyone including your friends. If they're forcing you and you don't have any choice, then lend him only few portion e.g. 20-50%, don't give full amount.
Even though he keeps forcing us to lend him our money, I think we can still refuse him because we don't want him to get deeper into gambling. This is for his own good and to keep him from getting more addicted. If he tries to borrow money from someone else, it's none of our business.
I would not be willing to lend if he used the loan for his purposes not for gambling and alcohol. But if someone lies to me because of a loan to use both of them then I will never care about that person other than collecting the loan, nothing more than that.
Yes, that's because we don't want to be blamed by his family for lending him money. Besides, we also don't know if he's lying or not because once he accepts the money and leaves, he can use it for whatever he wants. And if he doesn't have good self-control, he can go back to gambling to gamble again and try to win some money from gambling.