The more you kill, the easier it becomes to distance yourself. The more you distance yourself, the less you will hurt. The more easily you can bring yourself to hurt others.
Yes. SCP-1000 are just like us. That's what makes them so dangerous. We wiped them from history and memory. We dissolved their civilization and we slaughtered most of their species. Just ask yourselves: If they got the chance, what more would they do to us?