Guess what, after all he ended up returning $10 to his friend.
So I ask, did the friend do well in returning $10 to his friend or the returned $10 was not enough?
To me, in general, that seems wickedness of gambling between friends on a P2P because such friends are not worthy to be trusted considering the sentiments in playing to win.
I would say that is a daylight extortions amongst each others.
There is no refund in gambling because there is an unwritten agreement between physical gamblers to engage in this risky game. The other gambler who is asking for a refund is immature and should stop gambling. I am sure he wouldn't have given his friend any refund if he was the winner. The other one has a good heart and should be commended. However, it is better to gamble at a casino than gamble with friends because it could lead to some disagreements.
I have never played P2P gambling with friends and I don't recommend it to anyone. It seems to me that if you play against a friend in such games, you are no longer friends. You can play different games with friends, but not for money and not for bets, but just for fun, so that neither of you will feel bad if you lose. Money can damage friendship, and no amount of money can compensate for the loss of friends.
Some friends see gambling with each other face-to-face as normal. I used to follow a friend to gamble with his other friends and he has never engaged in any alterations because his friends are mature and responsible gamblers. I also observed that one of the reasons why they meet is because they enjoy this form of gambling. As they are playing, they are talking, drinking, smoking, and jesting and the place is just lively and enjoyable. But like you said it is not good to gamble with friends who are immature gamblers or don't understand gambling.