There is a large class of people who believe they are intelligent. But sadly all they have is complete confidence in their views backed up by some pseudo intellectual nonsense that they’ve either read/watched/heard without much understanding.
Or a better ability to rationalise some impossible position. That being said I can't help thinking that there is a certain callousness, that the ideal is so great that it's worth breaking a few eggs, a lot of eggs if necessary. That certainly was the mentality of those who perpetrated the crimes. Lenin, Stalin and Mao were certainly thugs, but I think they were first and foremost true communist ideologists. I think western intellectuels deliberately ignored the crimes in the name of ideology.