I have some theories why being famous can be a nightmare. What I've figured out is that nobody gets famous for actually being themselves. Well maybe some do, but it's rare. Their selling point is usually their perceived talent and talent is a finicky thing. And any person who is unable to act like themselves is bound for the insane asylum.
Being famous can limit your power so much, and so easily. But I think a lot of different types of people just wake up one day and realize they can no longer say or do what they actually want to. It's more than political correctness. People are literally shitting their pants over the dumbest stuff. Like really? Having a controversial opinion makes you nervous? Than you are weak, and it is that simple.
I don't think people are cowards. I actually think that Americans are just so annoying, and so child like that you are basically an idiot for dealing with anyone. Period. It sounds like famous people were more happy when they were independent. So one must get famous while being independent in order to be happy.