Many reasons of course, some lies, some true, some public..and some private. As the story unfolds, Michael was very famous from the beginning {of his life}. He started at such a young age, he doesn't remember much. His memories are so vague, he can't remember why a lot of people began hating him at THAT age. Well, one thing was that his sister's, LaToya, and Janet, weren't included. In his book, "Moonwalk", written a few years back, he stated that people would see them on the streets and shun them, saying they were "sexist siblings" and "they should let the girls be in the group." Michael, of course, had no choice in this whole ordeal, which was hard on him, because him and Janet got along well, at the early ages. Seeing and hearing this stuff made Michael very optimistic, and sensitive on the situation. When Michael was in the Jackon-5, he had absolutely no freedoms. He would have late-night recordings, and would have troubles in school. Most of his attention from his parents was on the business, they never gave him the attention he lacked, he was pretty lonely. After Michael grew up, and he moved on in his career out of J-5, he was thought low of to everyone in the music/movie industry. Brooke Shields once quoted that he was a "lowly-person, who needed help", plus some other things that cannot be said. Jackson did have some people of whom thought very high of him, Elizabeth Taylor was one of his best friends throughout the hard stages. He looked up to her, and vise versa. With the help of her, he got through the depression of his family members
(LaToya mostly) disliking him, and disapproving of
him.