Whatever it is, one way or another, they go underground and disappear with all our supplies. That is why they need us gone from the face of the earth.

They cannot have us hunting them down, pulling them out of their hidey holes and taking over their base and shelters. Just a few left as meager servants, I think maybe all those grateful illegals flooding in. They are used to crap living.

This was so easy to figure out. So easy a caveman could do it! (And may have before in another age).