The suspect frequented sites and forums that advocated a misogynistic perspective and his exposure to such content almost certainly nourished his growing hatred of women. Over time, hatred of women formed a core part of his self-identity. Toward that end, he lashed out against women for all of his failings, ultimately going on his murderous rampage.
One story on the recent contributions of misogyny to such crimes can be found at: In covering Elliot Rodger, writers aren’t shy about blaming misogyny and the groups that perpetuate it
Hopefully, in the wake of this terrible tragedy, the spotlight will be placed on the misogynist groups that, at a minimum, create a twisted narrative of women as a means of evading the actual or perceived problems their members face.