I think it is funny how they are judged.
Britney for instance, the harder they fall the more some people love it, yet they are falling usually from where the same people put them.
She is surrounded by people making money off her and "yes men", who agree with all her ideas. Really it is about the mighty dollar, the drunker Britney gets the better chance she will be caught doing something stupid, the better that she will end up in the press the more publicity good or bad the more money they make. It is a sad circle missing one component , that she is a person, flawed, young, trying to get by in a world of excess and under pressure most kids never deal with.
Yet you still hear kids say they want to be famous, but ask them why? Some don't know. Not all will say for my piano skill or my acting, some just want to be famous and I wonder if they understand what fame is.
Like if you are an amazing tennis player, being recognized publicly for your skill would by a by product=the fame. You don't want fame you want to play tennis, the fame just comes because you excel at it.

As for celebrities that become famous in their adult lives I think it is a different scenario as well, however, so many are still very odd, despite the fact that they should know better.