I get what you are saying....but for every Robin Williams, there is a Tom Hanks. For every Woody Allen, there is a Ron Howard.
What I guess I am saying, is fame does not ruin everybody. Some people keep away from the controversy, do not have tabloid issues, and generally lead great lives. I do not have statistics, but I would guess that famous people are not more prone to depression or drug abuse (etc.) than the GP.
Given the choice, I will take the cash and fame, and trust myself to keep myself out of the People magazines, TMZ, etc. Now I am 49 years old. Not sure I could say the same if I was in my 20's though.