Those indoctrinated by leftist thinking become largely incapable of making accurate moral judgments.
There is no happiness that isn't earned
That said, I have come to believe that the more committed one is to leftism, the more likely one is to become meaner.
More harm was done in the 20th century by faceless bureaucrats than tyrant dictators.
Badmouthing your ex-spouse rips the child apart
You will be a happier person if you don't do what you want to do, most of the time