First, I'm sorry that your little brother had to experience such immature behavior from fellow gamers. He deserved better. With that said, your little brother learned an invaluable lesson that the world is neither just nor equitable. And all it cost him is losing "loot" in a game, as opposed to being swindled for something more valuable (e.g. money) in the real world by criminals who are no less scrupulous than the gamers who ripped off your little brother. My advice to you and your brother is to keep playing games and not let the immature antics of some ruin your fun.