The real eye opener is that you can go to a memorial of such an atrocity, and feel the devastating sorrow
Yet you won't accept that in the same circumstance with the same choices, you'd probably do the same.
That's the lesson. Not that 'this bunch or that bunch' or this company, that company are inherently evil (though the totalitarians at the ideological extremes come pretty close) - Its that all of us have the capacity within, and we're all capable of supporting death, suffering and exploitation if we're sufficiently removed from it, and if it makes for us an easier life.
Just like, in the right circumstances we're (mostly) all inherently capable of the greatest benevolence also.
We're all individually subjective. Sometimes we do bad to others out of desire to do good for ourselves, our family, friends or wider group we seek to identify with.
It's our nature, a throwback to our evolution.
But that's probably getting a bit deep for a city forum.