I like it as much as I like sex. Even more when they're together.
There is no bullshit sob story. I like how pain feels, it's that simple.
The only time I ever hated it was when I saw it in my mother. She couldn't handle pain in any capacity and she'd cry and cry, and frankly it disgusted me.
Sometimes I experiment, inflict pain on others just to see how they react. It makes people a little less boring.