So am just curious to know if these little games are the one's that got to him or already developed such habit and to know if possible that the practice will continue elsewhere after leaving there when he lost the money and to look for means through gambling to recover it.
The person or people in question's gambling history should be traced. You can't tell me that the little get-together game is what led them to that level; it's not convincing to me.
Either one of them or one of them is a chronic gambler who wants to show off in every little opportunity they get, which is why they decided to take the game to a whole different level without even thinking about how others will view and look at their action.
This could be the sign of someone being addicted to gambling, but it could also be a sign of someone that is ultra competitive, and regardless of which one of those options is the correct one, the truth is that both can be very difficult to deal with, as those that are addicted will always be in denial of their condition, while those that are so competitive will make a big deal of even the most informal competition, in which case it is better for the OP to never organize a reunion among their friends in which they play some friendly games or this will happen again.