I think it is almost unquestionable that the Left’s belief systems have proven incongruent with the real world. Communism didn’t work and only survives as a pretext for despotism in North Korea and China. Welfare is a trap, and poor people’s lot in America has improved since access to it was term-limited. Higher taxes on “the rich” depress economic growth and throw people out of work. The list could go on.
With their gods having failed them, leftists have turned to cant, ritual, and hysterical repetition of their golden oldie playlist of slogans. And most of all, to demoinization of their opponents. It is fairly primitive, and often comic, with tinges of tragedy.
To paraphrase what I wrote here, the Left wants a society that operates according to its strictures. But those strictures are so at odds with human nature and morality that society often (though not often enough) rejects the Left's agenda. When Leftists cannot satisfy their power-lust in the real world, they compensate by imagining a theoretical world of doom. It is as if they walk around under a thought balloon which reads "Take that!"