It's that people are easily duped by fakenews, and rely on echo-chamber information gathering. Reality is largely irrelevant; expert opinion is disparaged, facts are "biased".
It's the same reason a majority of voters for Trump really believe that Obama is a secret Kenyan Muslim agent and that America is going to hell because of immigrants, global trade and equal rights under the law, and can only be saved by a racist, lying reality show shyster. People invent a reality around their established worldview.
Bookmarks