For some reason humans have a morbid curiosity about this or that. Celebrities on their way to hitting bottom has a plot all its own and the media hypes this up and tells you agbout it so much that people begin to have a vested emotional interest in it. Much like how I dont really care about football but I hear/see the games so much that I cant help but pull for the local team.
Then you have the women who channel their sexual lust into pathetic infatuation for the unattainable. The difference between men and women in this regard is the tendency for men to emphasize the physical, ie, lust. Women, however, tend to in my experience seem to really want to love these people on an emotional level from afar, which is a byproduct of how they deal with sexual relationships in general. And then there's teh whole hero worship thing that so many people get caught up ijn.
The media makes money off of you paying attention. If you catch the end of the movie you become emotionally invested into it, regardless of whether or not you actually like it, that you want to know the rest of the story. The media tells you at every turn what's going on until you want to know the rest. It sells. Therefore it continues.
I personally am irritated about it too. I'd rather learn about something important. The human obsession with celebrities taps into either our hero-worship tendences, our sexual tendencies (although they're expressed differently, but that's natural), and our morbid curiosity tendencies (ie Britney).
