Presumably if you're depressed, your positive feelings of self worth are also depressed. Does your question imply that a significant number of submissives are drawn to submission because they lack positive self worth? That they submit as 'rightful punishment' on themselves?
Most subs on here claim, I think rightly, to be strong, feisty characters and absolutely refute being 'doormats' or any other term that implies lack of self worth. Submission is presented as a positive, fulfilling choice or need.

Or do you think the impulse to submit lies in deeper psychological realms than this?