Now I am angry at my friend because he didn't keep to his words. Although I am still happy about the win, I wish he had given me back the $10. Then, I would have win bigger money.
There probably a reason why your friend failed to give back the money he owed you. And since you already won more than your friends owed you, you should forgive your friend already. Aside from that, you would be writing a different story if you lose the bet.
The thing called "if only" or "what if" is the things that keeps a person unrest. Better let go of the thought that you could have won bigger so that you could be happier on your bet result. Greed will never satisfy a person and may often result to misunderstanding between friends.