Sacrifice the Weak.
Alright. So if superpowerful aliens (like Species 8472 from ST) show up and decide “The weak (everyone but them) must perish”, I’m sure you’ll instantly volunteer to be slaughtered, right? …Thought so. It’s funny how easy it is to promote social darwinism when you think you’re at the top, but how you suddenly backpedal once you realize you’re just a small fish in a microscopic pond.