This argument doesn't work. I mean, people do horrible things to other people too (including killing them). So a dark way of looking at this is that people only care about things they form an attachment to (humans or animals or material objects).
People also get PTSD from killing other people. And militaries go to great lengths to dehumanize the enemy and get soldiers to be more ok with killing other humans.
People still often end up traumatized after doing that killing.
Even at a huge distance, drone pilots end up with PTSD fairly frequently.
So I don't think it's quite so black and white as only caring about things we have attachment to.
