Lucas' madness is derived from what appears to me to be megalomania. He has tremendous power over what we see in Star Wars, and he's pushing our tolerance for his changes.
Now, in the case of Michael Jackson (and this could happen to Britney as well), the problem is not power.
He had no childhood. He was singing and dancing with the Jackson 5 when he was, what, under 10.
From what I've heard, his father, in particular, worked the entire family very hard to make them famous. Michael never got to "grow up". As a result, he's living out his childhood now, and its getting him in trouble.
As for Britney...I don't know much about her. She was on Disney (Mouseketeer, right?), then she started singing. She's had more of a childhood than Jackson has had, but I'd have to say not much more.
Sam Lu,
Nice signature.