As I replied in this thread, https://www.democraticunderground.com/100215544975
https://www.democraticunderground.com/100215544975

Behind, beneath, at base of human cruelty is the near universal truth of poorly integrated, sick-selves who never learned self-worth nor self-control and thus seek-satisfaction through sadism.

Within and under the question why? is a deeper truth about the human condition.

Why do people confuse/ conflate the 'self' with 'non-self'?
Why is it so hard to understand the beam and mote?

The 'self' is objectively this "body-mind-sense-complex with a name and a story.
No good comes when the truth-value-worth of this 'self' falsely becomes subjectively mixed-up with objectively other selves.

We all understand human-subjectivity and tolerate (or try to avoid) those with out of-bounds subjectivity (partly cultural/social boundaries). Those whose subjectivity is too-far-out are not tolerated (prisons, mental hospitals, shunning, exile).

Now, if we could only teach our kids the truth about their "self', they would all grow up saintly without the need/desire for crushing others to feel good themselves.