You seem to be describing narcissistic antisocial personality disorder; ie. sociopaths. Bipolar is really the modern name from “manic depressive”, that is people who suffer moderate to pretty intense mood swings, along with a whole host of other pathological symptoms. Bipolar people are generally not bad people, and often are aware of just how destructive their disorder can be. Sociopaths, on the other hand, fundamentally lack empathy, and you do find that sociopaths often make the best con men simply because they care nothing for consequences, or for who gets hurt. They can learn to behave like a reasonable facsimile of a normal empathic person, but what they’re really being taught is simply to put on that face.
Not that people with extreme bipolar can’t be dangerous, both to themselves or others, but they’re still capable of all the emotions of a normal person, it’s just that they can swing wildly between manic and depressive states; euphoria at one end and severe depression at the other. Winston Churchill, for instance, is generally believed to have been bipolar (he called it his “black dog”). He was well known for periods of intense depression, and by the same token was also well known for at times seeming to have boundless energy (there were reports during the height of the Second World War that he was often getting by on only a few hours sleep a night).
As to Joseph Smith, maybe he was a sociopath, though the biographies I’ve read of him don’t really suggest that. A person can, over time, lose some degree of empathy without being a sociopath, and I imagine as Smith’s new religion began accruing followers, he probably became like some other religious leaders like L Ron Hubbard or David Koresh, getting drunk on the power, and perhaps even ultimately conning themselves.