~snip~
Absolutely agree with you. No one knows what would have happened if this guy had bet $10 instead of $1. It's ridiculous to think that the winnings would have increased tenfold. He could have lost that $10.

But this friend's behavior is something to think about. If someone is willing to lose a friendship for $10, then that relationship can't even be called a friendship. I would stop communicating with such a person as soon as possible.