It's because celebrities are supposed to be perceived as the role models for society.
They are supposed to be the people setting examples for us; yet all I hear about is how some celebrity got drunk at a night club, or how Brad Pitt walked out on Angelina Jolie when they have 5 or so kids, what kind of fucking example does that set?
They are made up by the media to be better people than the rest of us, just because they make millions in the careers that they chose, and what's amazing about this is that hardly any of them contribute ANYTHING to society at all.
I hardly ever see any movie or music celebs donating to charities or whatever (even though I don't even know how much of a difference that makes), nor do I see them volunteering in a community.
I mean, you know you fail when NFL stars are volunteering in communities, and Paris Hilton is driving while intoxicated. Great example, Paris, no wonder the world is so fucked.