One thing I find strange is how some people really, really like a 'star' and then go off them and almost deny that they ever liked them.
I've noticed this with some friends who I've known for a long time. They really loved someone and I'll remind them of it and they act as though they'd forgotten.
I'm not like that. If I liked someone a lot, I'll always acknowledge the fact, however embarrassing they turn out to bet in the long run.
Sorry, I meant to BE in the long run.
Actually OP, normal people don't really do this as most have a code of morals or tastes they stick to on the reg. The "fickle fans" you are describing sound as if they suffer from Borderline Personality Disorder. Go look this up and compare. The black and white, all evil or all good they ascribe to others. Look for relationship problems at work and with friends in this style. They usually relate to everyone and everything on these terms. Let us know what you've found.
When I was younger, I had mad crushes on various celebrities, which all faded in a year or two. Now that I'm older, I still have a residual fondness for almost all of them, I wish them well and speak of them fondly.
Except for Michael Jackson, whom I adored when I was in my early teens. That's too embarassing to admit to in real life. I mean, ick.