There are literally lot of things that he can be, but it is difficult to tell the exact one you're already picturing about him. Well, the story seem a bit strange, but at the same time, a lot of unimaginable things can also happen. Different situations or conditions can literally push anyone to doing crazy things, especially when we know for sure that no one is coming to help us.

Though, the risk he took could have easily go either ways as well, but he just happened to be lucky with a first try.
And as regards to why he chooses not to gamble again, I guess he made the right decision. Wins in gambling shouldn't be a motivation to keep gambling, especially when it is something you're not willing to do continually. The urge to keep gambling has resulted to addiction for a lot of people, so I guess he made the right call.