If you think this is all just playing devil's advocate and trolling there is something deeply flawed about your assumptions about how these people(alienated young white men) experience modern culture and politics.
Mental health issues, loneliness, social issues such as homelessness (living with your parents) and unemployment (underemployment, declining living standards), teenagers seeking borders and deliberately going for things that their parents does not approve, people seeking political change by first destroying the existing world.
But still it is hard to understand how it has gotten to the state it is today. This attack, the Christchurch attack are directly related to the chans. If Breivik was 5 years later, he would probably be there as well.
Plus other things are coming out of these boards that seem to start as practical jokes but ends up having major impact: Hyping of various cryptocurrencies, QAnon ...
(Oh, and as anyone who has seen a /pol/ meetup knows, they're not all young white men... alienated, though - yeah, I can see that...