Could you elaborate on mental disorder ?
Napoleon, by a chain of political events and victorious wars, was an autocrat in control of the main part of Europe. That was a reality, not fantasy of an ill mind.
Napoleon did not dream he was Napoleon: he was Napoleon.
Aspiring for power in troubled period, conquering successfully, are not mental disorder per se, especially when success at war gave a form of political legitimacy. Or please explain the difference with, say, Caesar or Cromwell.