Everyone would have their reason. I guess the biggest reason would be that they are emotionally stressed. They have to life like barbie dolls, fake everywhere they go. They can't make outbursts because the media would only play around with that and make it seem bigger than it is. Their fame is stressful and doing the wrong things might be a way out for them.
Or they have too much money and they don't know what to use it on so they use it on all the wrong things.
Same way anyone goes wrong. They are no different than anyone. Just more people hear about them. I came home drunk when I was a teenager and my mom caught me. Just my mom. I did not have cameras looking at me 24/7 so I guess I got away from the world.
A wise man once said that money and celebrity allows me to be who I really am. Everyone is restricted by societal norms and in some sense prohibited from being who they really are.
They do dr u gs, get mixed in with the wrong croud...stuff like that. Someone SURE is inquizitive today.
Because if they go right all the time, they will go nowhere. just saying :-)
The fame goes to their head. And all the peer pressure.
Tiger Blood... Just ask Charlie Sheen :D
They have to live*