Gee, Officer Krupke
The trouble is he's crazy...
Elliot Roger, the UCSB murderer, is being variously held up as an entitled rich kid, a frustrated nerd misled by geeky Hollywood types who somehow get the girl anyway, a product of the twisted masculinity of pickup artist nutjobs, and yet another example of the bullying patriarchate. Without necessarily completely rejecting any of those possible influences, let's just note that his real problem was that he was nuts.
My guess is that he was a psychopath. Unfortunately, this condition seems to be inborn and probably incurable. A large fraction of mass murderers turn out to be psychopaths, though not all psychopaths becomes mass murderers or even criminals.