They finally took BDSM sex out of the damned DSM version V And before anyone has anything to say about that..it was once a problem to have interracial sex. Oh and homosexuals where in there for a long time. Also, addictive internet use is in there now. So..for those who live in glass houses? I suggest you not throw stones.
When I was in college, I had a sociology class with a young woman(who happened to be white) who was a practicing dominatrix. She was taking the course to understand people's hang-ups. After class we talked about BDSM. I had learned that it can open doors in a person's mind. It is not about pain. It is more about looking into one's self by role-play(dominant/submissive, master-mistress/slave)and there is no sexual contact(Jane Weidlin of the Go-Gos is a dominatrix). My friend was also in the theater(bdsm is theater) on campus. She had a role in a play based on an Agatha Christie story. She was very good. I think the practice is a little extreme and I would not try it(maybe light bondage). Like everything else in the world, it is there to be explored. Each to their own tastes.
It's not about just pain. In some cases yes. The brain releases neurochemicals which can cause unbelievable space out highs. Some Dominants can train their play partners to enter that space by just a look or a word. Sub space can be addicting. But sub drop can be hellish. Theres so much more than sex or bondage to the whole thing. You can be sexually involved in one area (say impact play) but not in another area (like pony play for instance). What would you consider light bondage?