My personal experience doesn't constitute proof of anything (nor I'm a psychiatrist anyway), but the two bipolar people I'm somewhat close to are very analytical, stable guys. Then they turn around and become something else entirely - one of them has managed to build huge businesses TWICE, only to have a mood swing (usually after a few weeks without meds) and simply walking away, fight everyone, get a divorce and go to jail for beating someone over a trivial discussion. The other simply goes away (literally - leave home for weeks and pretend he's dead)

Then they "wake up" again. Quite disturbing...