Hiroyuki Nishimura has become a famous voice for disenchanted young Japanese
nytimes.com
nytimes.com
Also 9/11 was literally in their backyard. If someone flew a plane into your neighbors house you'd behave pretty irrationally as well
[1]https://news.gallup.com/poll/6964/top-ten-findings-about-pub...
They have complete electromagnetic surveillance of everyone and use this to harass incels and people without support into lashing out against innocents.
4chan is just one site where this happens and it has nothing to do with who owns it.