All three of those links are claiming right wing people are mentally ill.

Academics have all kinds of indirect theories for why people outside of academia don't agree with their politics. Ironically given the subject of the website, one thing they almost never do is just go outside of academia, sit down with people who disagree with them and talk to them as equals. They spam bot-filled websites like Mechanical Turk with surveys trying to prove things about the imaginary people in their own minds, and then publish "findings", but they don't actually talk to people.

The most obvious and logical explanation for why right wing people exist is that they disagree with left wing politics, believing them to lead to bad outcomes. Papers like those three are a dime a dozen, but one thing you'll never find is studies that just directly ask people disagree with common academic beliefs. Instead it's taken as axiomatic that leftism is moral and correct, so anyone who disagrees must have some other deeper psychological reason to disagree (loneliness, reading the wrong websites, not getting enough sex, whatever). Lots of non-replicable studies get produced, grants are awarded, and academics give lots of interviews to the NYT about their search for One Weird Trick to convert people to their worldview that doesn't involve any actual policy changes.

The professors doing such studies should look in the mirror. If they're saying social isolation and informational monoculture leads to extremism, then it's hard to find somewhere more isolated and monocultural than universities. But of course they lack sufficient insight to consider that.