Humans think of evolution in terms of progress and advancement. This final errand will be the catalyzing event precipitating a new era on Earth, akin to the meteor that felled the dinosaurs and ushered in the Ice Age.
Humans respond to fear in two simple ways: fight or flight. There’s no shame in getting the hell out of the way.
Human beings, you see, have no inherent value other than the money they earn. Cats have value, for example, because they provide pleasure to the humans. But a deadbeat on welfare? Well, they have negative value.