I used to think this was a coincidence, that leftists really did have a goal towards which they aimed, that there really was a predetermined endpoint to their opposition to "the system."
Turns out that's not really true. The base ideology behind modern leftism is "critical theory," which states that the criticism of the existing system never ends, quite intentionally. So there quite literally is no way to compromise with leftists, since any concession is by (their) definition just a prelude to the next criticism.
To be fair, a whole lot of leftists are probably unaware of this.
Oppositional defiant disorder
From Wikipedia:
Oppositional defiant disorder (ODD) is a diagnosis described by the Diagnostic and Statistical Manual of Mental Disorders (DSM) as an ongoing pattern of anger-guided disobedience, hostilely defiant behavior toward authority figures which goes beyond the bounds of normal childhood behavior. Children suffering from this disorder may appear very stubborn and often angry...