Apart from the prosaic deception of faking skills one doesn't have, work environments often require one to adopt patterns of behavior that are very far from any way one would normally act. There are limits to this. On the other hand, people have been know to resign from certain jobs because they didn't like who they had to be for those jobs. This could be explained by saying that the self required for this job was too different from the real self to be comfortably faked. On the other hand it could be explained that the self that had to be developed to master the job did not sit well with all or some of the other selves, or involved suppression of other, more central aspects of the personality.
Actors seem to relish playing people who are wildly different to themselves.
Not liking the character doesn't seem to be an issue. If there were just one true self, and all the others masks, one would expect the dropping of masks to make people happier, not mentally ill. Against this it may be argued, with some justice, that personality organization is not the same as brain organization. However, this is more a failure of imagination than an argument. Doing so would avoid the problem of explaining why one had it and not the others.