A friend was told that the CIA had such a psychological profile of lefties back in the 60’s. As I heard it, the liberals are extremely upset that the real world does not match their utopian fantasies, or they are unable to recognize that the real world is imperfect and not the way they want it, whereas a healthy person understands that reality is not the way we all wish it to be.
It’s a tough one, because there are people for whom that’s true in the ‘moderate’ or ‘right wing’ side of the political spectrum, as well.