@SuperOniichan Some can, much like how drugs, gambling, etc cause addictions. People like pleasure, and people want the feelings they get from the activity causing the addictions. In fact, if you ever saw or heard of the "Hellraiser" movies, they play off the idea of the pain/pleasure crossover.
Roleplay in general actually more common in sex than people care to admit to, and you can see a lot of the influence oddly enough in manga/anime. Think about the many themes used: harems, crossdressing, loli (yes, this is as well), incest, etc. In a way, they are playing off the fantasies that people (both men and women) possess. For S&M, it plays off a version of the Lord/Slave (gender doesn't matter for either role in general) idea, and can be combined with quite a few different other themes, such as the pain/pleasure combo.