The Lessons of Cho Seung-Hui Killings.

While many of us want to argue back and forth about the lessons learned from this killer for and against Christianity, exapologist wrote:
I'm worried about the extent to which this massacre is being used to make our pet points, without taking to heart what happened here.Here are two links talking about the treatment Cho Seung-Hui suffered from people in general. See here, and here.
There is a pattern. A kid, or group of kids, are picked on and alienated from their peers. I'm not talking about an occasional jab, but a systematic, coordinated rejection of a child as a non-person. The kid internalizes the message. It builds up until they can't take it any more, and so they explode -- with lethal consequences.
Why is it so hard to learn this lesson? This sort of systematic alienation is just too much for the human psyche. We're essentially social creatures, and can't survive this sort of global rejection. Can't schools, or at least parents, raise their kids well enough so that it would never occur to them to engage in this sort of bullshit?
What is wrong with us that we cannot treat people who are different from us humanely and with some measure of respect?