It's no exaggeration to say that many celebs experienced difficulties, most notably rejection, as children. There's a famous line in the musical Chicago which goes (something like) "that's because none of us got enough love in our childhoods. And that's showbiz Kid." That rejection spurs many people into a) wanting to make something of their lives, b) actually making something of their lives, and c) by doing so, receiving the appreciation they lacked as children. However, they discover that, no matter how much they are loved by the public, nothing makes up for the real love they need: parental, family love. And, because they've experienced rejection during their highly influential youth, they often feel undeserving of appreciation and success when they eventually get it. If success makes their lives easy, they sometimes sabotage it themselves - Amy Winehouse being a prime example.