Why would a fan care if a member of the team he roots for is a jerk? Is really dumb? Treats little kids and old ladies badly? I don't know. If I had to guess, I'd say it's because a lot of fans want to believe that the love they have for their team is shared by the players; that this affinity bonds them to the players. When it looks like those players care more about themselves than the team, some fans might feel a bit like they themselves are betrayed. Hell, I don't know. What am I Frued?