There's a term for those people you don't like. I think it's "bandwagon hoppers". :\

I don't think bandwagon hoppers are legit, so I'm not one. I stuck with the Falcons when they sucked in the early 90s, and I was with the Braves until they won in 95 (well, not "until", because I still am). I don't have the time to follow the teams as much anymore, because I have other priorities these days, so I guess I don't consider myself as much of a fan anymore simply because I don't take the time to follow the progress of my teams and their players as much as I used to. :\