So, are the killings misogynist extremism? Or were they the effect of a mentally ill individual who just so happened to perseverate on and be disturbed by his inability to relate to women? When I read about this story, I don't see a normal man attempting to exercise some kind of "misogynist extremism." I think that's an intellectually lazy argument to make that's made strictly to score some political points. Instead, I see a poor kid that should've been getting some help, didn't, and ultimately cracked.
Now I partially agree with this, but if he were part of a racist group, or posted his thoughts on stormfront, would this change your opinion? What about if he was part of a militia? What if he was part of a church? A cult? A group that advocated for the violent overthrow of the United States government?
From what I've seen online, these "Pickup artist" groups are bad, and they advocate a lot of bad behavior. They perpetrate this weird mythology that women are simply video games, if you push the right buttons you will get access to their vagina.
I am not saying that the groups caused him to go over the edge (because it's complex, you can't pin an illness like that) but what I am saying is that it is relevant that he was part of this culture and it helped reinforce (directly or indirectly) his views about women.