Granting the exceptions that all generalizations allow for, conservatives believe that those on the left are wrong, while those on the left believe that those on the right are bad.
I'll grant that there are lots and lots of liberals who feel this way. But Prager's blithe dismissal of similar phenomena on the right suggests he's not dealing with the issue honestly. Because there's lots of conservatives who think that liberals are evil. For example: I was attending a conservative evangelical Mennonite college in 1992 when Bill Clinton was elected president. I was one of the few students to openly support Clinton for president that year; many of my fellow students and faculty warned of literally Biblical, literally Apocalyptic consequences if he attained office. (The night of the election, a student in my dormitory openly wished for Clinton's assassination; I chalk that up more to immaturity than any actual desire.) This was not -- and is not, I think -- a narrowly held view. The whole existence of the "religious right" -- which a not-insignificant part of the conservative coalition -- is predicated on a Manichean view of the world: There's not really a distinction to be made in these circles (Prager's opinions aside) between "wrong" and "evil."
Prager might respond by saying that he's speaking only of "elite liberal journalists," and that "elite conservative journalists" don't demonstrate this behavior. But, uh, Andy McCarthy is making a career right now out of his belief that liberals and terrorist Muslims "are working together to sabotage America." Dinesh D'Souza took a different route, writing a whole (widely panned) book about how the 9/11 attacks were a response to American decadence unleashed by the left. The whole Tea Party movement is predicated on the idea that Barack Obama is a budding tyrant -- a belief promoted by, um, the conservative media. These are not the words and ideas of people who think the left is merely wrong; they're born out of a clear belief that liberals, if not inherently evil, at least act in evil ways.
Second, when you don’t confront real evil, you hate those who do. You can see this on almost any school playground. The kid who confronts the school bully is often resented more than the bully. Whether out of guilt over their own cowardice or out of fear that the one who confronted the bully will provoke the bully to lash out more, those who refuse to confront the bully often resent the one who does.
This analogy makes. no. sense. People LOVE the guys who stand up to the bullies -- in almost every case, almost without exception. That's why liberals and conservatives alike are fans of "Star Wars" "Karate Kid" "My Bodyguard" and virtually every great movie that features a confrontation between powerful evil and underdog good guys. It's the ultimate bully versus the standup guy scenario.
Where liberals might differ from conservatives is discerning who is a bully and how to deal with them. Liberals haven't always been right on this score, but neither have conservatives. And I'll go ahead and say this: Almost all of populist politics -- whether practiced by the left or the right -- can be boiled down to a powerful cultural desire to stand up to bullies.
In any case, Prager's argument is silly. It suggests that he doesn't actually know that many people on the left -- and, weirdly, maybe not that many people on the right.