A fifth is that, given the circumstances (the relatively recent destruction of the Maccabean kingdom and Roman conquest), for a Jew who believed that his religious scriptures actually meant what they said to expect the imminent arrival of a Messiah was not "lunatic" at all -- and if the Messiah is coming, why should it not be one's self, if the signs seem to point to that?
That's actually so close to the truth as to be a devilish trick. :-)