One thing I've learned is that there are as many ways of doing and experiencing BDSM as there are people doing it. My opinions, therefore, apply only to myself--my own desires and experiences.
BDSM had nothing to do with abuse to me. There can be pain involved, but it's the pain of intense emotion and desire, not the kind of pain caused by abuse and contempt. I've never had anything but the deepest respect for the subs I've been with, and they always know that. Submission means nothing to me unless the person has something worth giving up. I don;t deal with masochists.
That being said, I know there are subs who are in it for the raw pain, humiliation, and punishment, just as there are Doms who practice BDSM out of a basic hatred and rage for the opposite sex or for anyone who might dare to love them. Those are deep and dangerous waters, though, and I stay out of them.
The original question amounts to asking, "What causes someone to enjoy BDSM?" and that's a very difficult question. I had all sorts of theories at one time, but now I tend to agree with those who say it's something we're born with, hard-wired into us. It seems to be some sort of primal mating beahvior. Some of us have a need to act out these deep feelings of the male as aggressor and controller and the female as submissive and controlled, and we experience such play as intensely erotic. That seems to be true for me and the subs I know, and that's about all I can say about it.