Not saying that’s what happened in the Kirk case, but the reason video games are prevalent in such cases of violence is because they are a good recruitment tool for agents all along the political spectrum to nab fresh blood. In the past, cults used to do the same thing with music or religion, or social activities like festivals, but the playbook is the same. From what I can tell, predators are going to use whatever people do socially to target them as it’s the easiest way to build trust and demonstrate shared values.
Quite a few good points - but I would limit how much blame one puts on the web, and the obviously unhealthy influences and ideologies found there.
And bear in mind that 99.9999%+ of online young men are not suddenly going out and killing people. Sadly, humans' obsession with rare violent acts leads journalism into providing us with an extremely unrepresentative worldview.
(And imagining the Kirk killing to be part of some huge nefarious liberal plot is just a "politically useful" conservative delusion.)
And also that young men were occasionally doing political-looking violence - for random-, crazy-, or idiotic-seeming reasons - long before there was a web. Once the facts came out, John Hinckley Jr. was not an ideological actor. Nor an enemy agent. Nor part of any conspiracy. Just a sexually obsessed lone nut job.