Why is it, that you are not suppose to change your team?

In the mid-90s, I forget what the Mets had done to piss me off, but I had sworn off them and even tried to become a Yankees fan. It was before the Yankee dynasty had started so it wasn't a bandwagon thing, I just needed a new team to root for. It never felt right. I think I lasted 2 months maybe before relapsing and I've been fucked off the wagon ever since.