I tend to be more of a sub than anything else. I think this is because in my "real" life I was always the guy who had to be in charge. To be under the control of a stronger guy gives me a chance to drop that life and relax.
Also I had a difficult relationship with my father. He was in the RAF and was sent abroad soon after I was born. I was 5 before we met, and he was never the dominant father I felt I needed. So serving a Dominant guy makes me feel more "normal"
I can only respond to this from my perspective as a dominant male.
I've had more than my share of subs/slaves during the past 30 years and the ones whom I find need the submission the most are the one with the most power in their vanilla lives. I've had judges, lawyers, doctors, and nurses. One of the main themes I've found in all of them is their abilities to control others in the manner of life or death, or some form of it.
A lawyer may represent some of the most vile person on the face of the earth, but they will do their best to defend that person. A judge may preside over a case in which a teen ager committed an adult crime, and while this may be that teen agers first offense, it may be required to imprison that teenager for a number of years with adult felons.
A doctor may fight to save the life of a child, but eventually the fight will be lost. A nurse may have to attend to a child whose parents have been killed in an accident and not allow their emotions to effect their behavior or the manner of treatment.
All of these positions come with very intense and lasting emotions. Emotions these people may want to forget for a time. Emotions that they find hard to control and need an outlet for. This is where their submission to someone in a dominant position is most relevant. They are no longer in control of their "fate." They no longer control the "fate" of others. Even if for even a short time, they are free to not have to control others lives, but to have someone else control their lives. No matter the gender of the submissive, they all crave this. Well, at least, this was my perspective from the slaves I owned at one time or another.