Why do aliens want the fittest/most resourceful person to survive?
Won't such a person be a threat to them? Because such persons can create a resistance against them!
shareThe movie doesn't tell us what the aliens want
All we know is what the characters know: they're getting killed off one by one, and they have the ability to choose who's next
That said, the commentary track floats the notion that the aliens saw themselves as helping us. They figured we needed to depopulate or risk extinction, and they gave us the power to decide who survives