In order to make their story come true, the Takers have to put an end to creation itself—and they’re doing a damned good job of it. - Daniel Quinn

The world of the Takers is one vast prison, and except for a handful of Leavers scattered across the world, the entire human race is now inside that prison. During the last century every remaining Leaver people in North America was given a choice: to be exterminated or to accept imprisonment. Many chose imprisonment, but not many were actually capable of adjusting to prison life.
"Yes, that seems to be the case."
Ishmael fixed me with a drooping, moist eye. "Naturally a well-run prison must have a prison industry. I'm sure you see why."
"Well…it helps to keep the inmates busy, I suppose. Takes their minds off the boredom and futility of their lives."
"Yes. Can you name yours?"
"Our prison industry? Not offhand. I suppose it's obvious."
"Quite obvious, I would say."
I gave it some thought. "Consuming the world."
Ishmael nodded. "Got it on the first try."

Pursuing an evolutionarily unstable strategy doesn’t eliminate you instantly, Jared, it eliminates you eventually.

Mankind was not needed to bring order to the world.