What I took away from this experience is how the mentality of gamblers can change after a win. The thrill of success often leaves us wanting more and in this case it seemed like my friend was caught in that cycle, as I was feeling before too and he was unable to honor his word probably because he wanted to keep increasing his gains and bet more. It's a reminder that the brain is never truly satisfied when gambling, there's always the desire for more. I believe that friend deserves an advice, but I don’t want to embarrass him myself, is there a good way to talk to him without making him feel that Im indirectly asking him for the money he promised me?
One thing you should understand is that human desire and quest to make money is endless and as such they will continue to fail there promise because of wanting more and more. You wouldn't blame your friend though, because I myself has made a lot of unfulfilled promise. People get overly excited and make silly promise and failed after making such promise. so in such case I see it as normal. but in some case it reduces a person personality because your words or promise may not be much valuable or respected by your friends.
As a gambler, it's easy to get caught up in the excitement of the game. In the heat of the moment, you might make promises to friends that seem reasonable at the time. However, once the game ends and reality sets in, you may realize you have made commitments you regret. Doubt creep in and you cannot help but wonder why you made such promises in the first place.