I hate to break it to you, but I imagine this won't be the last time a lonely angry teen takes out his frsutrations in the most violent manner possible. Yes, we have the 'why', but we don't have the 'how'. Last I knew, kids weren't born with misogynistic tendencies.
Disregarding all attempts to actually discern what would drive a human being to do such a thing as being 'just crazy' accomplishes nothing. Every time these shootings happen, we're all treated to a media circus where every tom, dick and harry points fingers. The immortalization the killer is subjected to is appaling and occurs like clockwork, but I do believe there needs to be a seperation of the killer themselves and their motives, namely in how and where they manifest and grow.
That we've got members here able to grasp some semblance of relatability to how the killer ended up as he did shouldn't result in hysteria and accusatory remarks, it should only emphasise that, though it's not going to make people pick up a gun, there are people who experience similar debilitating frsutrations.