I have known several leftists and have found what others have said about them is true: they think they are morally and intellectually superior to those who aren't leftists. More accurately, anyone to the right of them.
I understand them intellectually but not emotionally. I do know that all of them are fuzzy-minded thinkers, although they never know this. They think they are brilliant. They have no idea it's all about their feels.
They think those that disagree with them aren't merely mistaken. They think they are bad people - evil.
If they are vegetarians, those who eat meat are barbarians - evil people. If you smoke and they don't, then you are evil. If you believe in some kind of God and they don't, then you are a bad person. Since they are socialists (socialism and atheism go together) and you aren't, then you a bad person - a patriarchial, capitalist oppressor and religious fanatic wanting to turn people into slaves. If you believe in the Second Amendment you are an inbred Morlock living in Flyover Land and clinging to your guns and religion. Have doubts about feminism and you "hate women."
They think they can read people's minds - or perhaps they think they know what people "really mean" when they write or say something.
The self-deception of a leftist is really quite scary. They never know just how self-deluded they are, though.
They are always animated by hate and envy, which means they always want to destroy - everything.
When these people get some kind of political power - and all of them believe in political power as being god-like - they are convinced they have the right to move people around like checkers. For their own good, of course. And if lots of people die, too bad. After all, they're evil and therefore not really quite human.
At one time, in the past, leftists thought everyone could develop god-like powers. But they've given that up. Today, they think only they can develop these god-like powers. Other people - just clay to be molded as leftists see fit.
At one time in the not so distant past leftists would travel the world, visiting totalitarian societies such as Cuba and the Soviet Union, deluding themselves they were bastions of freedom.
They have given that up, unfortunately. Now they've turned their efforts into turning the West into totalitarian societies and so far have done a fairly good job in some ways.
The 20th Century was the century of leftism - Nazism, Communism, fascism. Of socialism and atheism. It's been estimated up to 200 million died - after all, who counts peasants?
Erik von Kuehnelt-Leddihn made the argument that the Marquis de Sade was the founder of modern leftism. De Sade was a sadist and a sexual pervert (I have found almost all leftists are sexual perverts), and considered people no better than insects. He contemplated with satisfaction that perhaps humanity might destroy itself. How can anyone half-way normal understand such a mindset?
Leftists aren't systemic thinkers, except for one thing - I'm a good person and always right - and you are evil.