Why do Dodger fans act like they’re part of a Dodgers gang?

I grew up in LA and used to wear a Dodgers hat and then moved to San Diego and now wear a Padres hat, and now every time I pass a Dodgers fan they make a threat and try to start a fight. I really don’t care about either team, it’s literally just a hat. Why do Dodger fans act like a baseball team is a gang?