I think it's important that some clarity be had, whether you're talking about real-life experiences or fantasies. As a lifestyle, 24/7 slave of more than a decade, I will say I loved my Master, and I loved my life, and I trusted him absolutely. There was nothing in that relationship which harmed or psychologically damaged me- except it's ending, which, while amicable, was also devastating.
Most of my fantasies of slavery though, are of the non-consentual kind. Brutal, unwilling, kidnapped or imprisoned, shackled and branded, sold on an open market to the highest bidder, or marked for public use. That sort of slavery, in the real world, has got to be monstrously damaging, psychologically, as well as physically, and I'd not want to experience it any more than I would a "plain old traditional" rape, or a date rape.