I've always had a fantasy about being forced to serve someone completely. But I'm a very successful and independent person in daily life. Why do high-functioning people often want to be submissive?

The pattern you are describing is so well-documented that it has almost become a cliche in BDSM communities, though it is no less true for that. High-achieving, controlling, or responsibility-bearing people are among the most common people drawn to submission. The mechanism is counterintuitive from the outside but makes practical psychological sense.

People who carry extensive control over their environments: who make decisions that affect others, who maintain professional authority, who are relied upon constantly, rarely experience the particular relief of having that responsibility temporarily lifted. The ordinary world provides few acceptable spaces for a competent adult to simply follow direction without shame or loss of status.

Submission in a consensual D/s context provides exactly that space. The structure is clear, the expectations are defined by someone else, the decisions belong to the Dominant, and the submissive can inhabit that structure without it touching their identity or competence outside it. For people who are almost never off-duty in that respect, this can feel profoundly restorative.

There is also a trust dimension. The very independence that makes submission unusual for you in daily life means that the act of trusting someone enough to submit carries significant weight. The choice itself, made by someone who does not need to cede control but chooses to, is part of what makes the experience meaningful.

You are not contradicting yourself. You are describing a form of rest that your everyday life does not supply.