The first loss should be the first and the last mistake, slap him into the reality that gambling isn't really for profit-making. The only people should waste their money on gambling are those luxurious people who think gambling is for entertainment only.
I understand this. But it won't really hurt you to help once and tell that person to change or try to be a better person. At least you warned and reminded him so he knows there won't be a second chance of help from you.
Help once? Do you even understand how hard it is to be addicted in something? Reminding him once won't help at all, it will just keep on coming back if you will just do it once. That kind of help is not needed, better ignore him if you will just do that half-hearted help of yours. If you will not be there for him, your totally useless in helping him.