Why do people love dirty laundry?

I don't understand why people like to hear about others' failures, misteps, demise, etc. I think it's terrible how the press keep on celebrities who are going through problems: Paris Hilton, Britney, Lindsay Lohan. I don't like to see people in pain, but I admit a part of me feels good when I hear about someone else losing their job, getting caught cheating, or getting a divorce. Sometimes I feel like I'm the only one who gets down - well, I think that is because I'm sensitive, and don't bounce back well. Everyone has crappy days at times, but many people seem invincible. I know a few people who seem to have it all together (perfect job, perfect husband) and it doesn't seem fair because they're not any more skilled, talented, or better looking than I am. So, when something tragic happens to them, I'm like, good, at least I'm not alone here. That sounds bad, but it must be human nature because many people take it a stuff further and trash others who are obviously down and out. Why??