Oh please, the man was not Ted Kazinsky in a cabin. You do not know him personally i presume? He was obviously relatively successful at being integrated into society, was employed etc. Had good jobs, had failed marriages, girlfriends. Not on any FBI watch lists, not on anyone's radar... THAT is what makes him so scary. Everyone will feel so much more comfortable once we have a label to slap on him, so we can know where to direct our anger at this horrific event.
IDK, just as likely since psychopathy runs in the family... that he snapped after several days without sleep, abusing alcohol and drugs... and finally slid into total insanity.