And the greatest atrocities of humanity have been made with social co-operation.

That's trivial. Atrocity goes hand in hand with power, the same power that decimates a whole people also builds the city over their graves. The powerless cannot challenge power, there is nothing honourable in ineptitude. If you want to feel good about yourself for being weak you can go back to church and pray that a god will save you, but for those who wish to triumph in the world there is only one path available, and it is not bloodless.