Because it seems like for every suicide bomber there's a charity that gives toys to sick children. For every reckless driver there's a police officer who doesn't get paid very much. So you'll forgive me if I have trouble propelling myself over the horizontal distance to your conclusion.
The trouble is that your view represents just as much about you as it does about your subject. We're all looking at the same statue, in effect, but you picked your seat.
So when you look to The Holocaust and marvel at the evil men can do, when you look to the Mars rovers* and shudder at what we can accomplish, when you look to Wikipedia (where you looked to The Holocaust and the Mars rovers) and wonder that it works at all, you are making a choice.
YES, you are.
You are choosing to make a single example into a microcosm of the whole. And even if you can explain at length why that reasoning is valid, you must concede that your conclusion was not self evident, that it required a decision on your part.
And knowing that it was a decision, I now look to YOUR nature before I follow you any further.
A universal theory of human behavior, attractive as it seems, might be a more wily idea than you think. I have good reason to think so.
For all my experience, for all my learning, for all my careful consideration, I have found but one sparkle at the bottom of my pan.
The only consistent thing about human beings is that they surprise me.
*You know the ones I mean. Spirit and Opportunity.