Made a Profit
If you were somewhat of a loner when you were younger, then you might understand the vulnerability that comes along with that. Many people around you are probably aware of your lack of social standing and choose to be mean in ways that they really shouldn’t.
Placing a bet on a girl doing something is the oldest and most boring trick in the book that really isn’t even funny. Obviously, this girl was going to say yes to a thing like this, at least make the bet slightly harder. At least he gave her $10 after realizing it wasn’t a nice thing to do.