Is it “won’t happen to me” mentality?

Mostly. Majority of people on this site is more or less the same as reddit, westerners. A lot of them privileged, sheltered westerners. For them, especially the Americans, the war is not real. Their grandfathers weren't dying in nazi death camps, their fathers weren't dying from drugs or alcoholism or poverty during economical transformation. For them it's a show to watch on TV, and since we here are telling them something entirely different than the narration they got used to in last two years, they get cognitive dissonance and lash at what cause it the most. Even including the sources they were taking as a gospel before.

And some are worse, those that are more or less aware, that it was their grandfathers who gained their golden age when ours were dying in camps, and their fathers gained their end of history when ours got pummeled by transformation.