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?
Well I don't think you should use indirect way to talk to him rather he should know that you guys have already reach into agreement or into discussion that he would give you 10% knowing too well that you aren't the one who asked him for that amount from his total winning, but to me even as that if he is not willing to give you that money promised by him then I will suggest you should leave him alone because if you try to push further he would see you as a begger rather, he was the one who said to give you 10% so let it come from his mind to give the percent and if he refuses then you can leave him alone that is all.