Dear Gwen... I don't know if anyone has really answered your question..
not that I'm sure that there is a complete answer, or one which applies to everyone. One theory is that it is genetic, that a predisposition to be attracted to bdsm is somehow hardwired into the brain from birth, a condition like adhd or bipolar disorder having mostly to do with brain chemistry. This is both good news and bad news. The good news is that you are not to blame, since you cannot control what you were born with. The bad news is that, like alcoholism, there is no cure. The desire will always be with you. The best you can do is to try to find constructive ways of handling it and integrating it into your life. I think that one of the biggest difficulties for me personally and perhaps for many other people is the obsessive quality of these thoughts and desires. There have been times when I felt as though they were taking over my life, to the detriment of taking care of my responsibilities, pursuing other interests, etc. A therapist who I saw for a period of time who specialized in such matters tended to look at it as an obsessive-compulsive type of thing and recommended that I take Prozac to ameliorate it. Unfortunately the prozac did nothing but make me impotent. It didn't really change the way I felt.
Another theory is that it is learned behavior, usually stemming from some childhood or adolescent incidents of abuse, whether sexual or otherwise, or coming from a background where one's signigicant others related to each
other primarily in a controlling and/or dominating way. This is certainly true in my case. If you are imprinted with the idea when you are young that this is how men and women interact, you will tend to follow the same path.

To me, another and perhaps even more important factor is alienation... Many people feel isolated and empty inside even though they might be surrounded by other people, be married, have a comfortable life and friends. In today's world there are many factors that contribute to this... the breakup of the family, lack of community, etc etc, not to mention whatever personal traumas the individual may have experienced which may cause them to kind of shut down emotionally, withdraw behind a wall that nothing can penetrate. This drives people to seek more extreme experiences as they find themselves unable to find satisfaction in their normal or vanilla personal relationships and posessed by an inner restlessness, needing more and more powerful stimulus to break through the wall and be able to really feel something.

Lest this sound too overwhelmingly negative, let me say that I do believe that it is possible to have a safe, sane and consensual bdsm relationship which is rewarding for both parties, but it requires a good deal of understanding and care. bdsm is like a powerfully addictive drug, which may bring you great pleasure and take you to new worlds of sensation, but needs to be handled carefully, lest it take you to places you don't really want to go. Doubless there will be readers who feel that all this thinking about it just spoils the fun, and I'm not trying to rain on anyone's parade. As someone who has pursued an interest in this stuff for thirty years or so, this is a subject I've thought a good deal about. If anyone can recommend any books or sites offering more information on the psychology of personality development as related to bdsm, I would be interested to hear about them. I have tried looking into some of the academic psychology sites but most of them you have to pay to subscribe to and the scholarly papers they publish are overburdened with jargon and overly technical. If you know of something readable on the subject then by all means turn me on to it. Meanwhile, play nice, kids...