It's best not to pay too much attention to him, because when he loses everything he will look for you, and that's the moment for you to advise your friend, forcing him to talk to him will only cause you heartache.
The Op made the right decision by just standing far away and observing him, and it's even more interesting that the person the player who won the game is avoiding doesn't even care about that, which he had promised him.
If he could have just come clean and said, Sorry buddy, expenses and some other things took away that which was just won, their friendship will just be the way it is," he could have also even gotten free advice on how to effectively manage his funds in case of next time.
Anyone that accepts this are probably pretending, in this case no one will feel less hurt just because the friend said sorry I have expenses, this doesn't make the friend a better person, it is only a man of integrity that keeps their promises, man to man it is a must, even in friendships, so that you both can respect each other and also it will make your friendship to be stronger and built on complete trust.
For what the world have turned into today I will prefer to stay away from any friend that don't like keeping their promises, it reflects a part of them that they can't be trusted and rely on, this is just me though, as I have come from dark places where friends aren't so loyal.