Altruism, cruelty, and sociopathy

I have been thinking recently about whether lack of altruism is a sociopathic, but not necessarily sociopath-specific trait. I have also been thinking about whether, if altruism is the result of an excessive amount of empathy, is cruelty necessarily the result of too little empathy?

A reader recently wrote questioning whether he could meet the diagnostic criteria for ASPD (Asperger's). After listing the behaviors that he considered sociopathic, he equivocated:

Then again, I do care about my friends and all. I'm not a hundred percent sure, but I think I feel a little bad when I walk over someone's heart. And I never walk over someone with the sole intention of hurting them. So I am definitely not a sociopath. Yet, if your blog is anything to go by, then I can't be too far from being a sociopath (a mild sociopath, of course).

My response:

Yeah, I was just going to say, not all sociopaths are out there hurting people just to hurt them. What does that even mean? That you gain pleasure from their pain? I never hurt people to watch them suffer. I do it for my own purposes, to get in a better position, etc. I feel like a good analogy is the stock market. When you short trade stocks you are basically doing a wealth transfer from you to whomever you are buying low from and selling high to. It seems like you would have to be a sociopath to engage in that sort of business, no? But people do it all the time. They just probably don't like to admit that that is what they are doing. Same thing in the emotional/social realm. You make alliances, you may consider certain people "on your team," in a way of self-insuring should disaster strike. But people who are not on your team are people who will either gain from your loss or vice versa. That's just the way of things in this mostly zero sum game.

Is my worldview cruel? Does seeing the bulk, if not the entirety, of human relations as a zero sum game part of what makes me a sociopath? Or am I just seeing the world clearly?