This is an extreme example of why you don't screw people over, even if you lack empathy.

Nobody likes to be screwed over, but most people take it in exchange for other perks (job security, for one). But people have a screw threshold, and if you cross it, this is what happens.

Now, this is not the main reason not be a jackass -- on the other side of the spectrum, you usually get much in return for being nice (if only for just differentiating yourself from everyone else) -- but that's another story.