No evidence has been presented that he was bipolar except his ex-wife saying it. Which isn’t a medical diagnosis.
People like to say, “Well, only a mentally ill person would do that” simply because they can’t comprehend somebody with a worldview that different from their own.
And yet, right now, in Syria, and Iraq, and Libya, and elsewhere there are guys field stripping their AK’s who are sane, stone cold sober and very serious with that worldview. Dismissing them, and thus guy, as merely nuts is a rather dangerous underestimation.