Many of my friends when they are in trouble don't have any money, when they borrow and promise to give me extra money when they win a bet, when they win they disappear, when the money runs out they meet me again, So I can judge that friend, in the future I will not give him any more money, whatever the reason, because for me people like that don't keep their promises when it's hard to get to know old friends, when they're happy to get to know new friends.
GxSTxV, let that friend enjoy the win, even though you are not given any of the winnings, you don't need to collect it, so you can think about it yourself in the future, just once help him understand betting and so on.