No," Morrow said. "I can't accept that. I don't always agree with the Planners. But they aren't killers." "You think not?" Uvarov laughed again. "The… - Stephen Baxter

We'd carve a place out of the wilderness—"
"But there is no wilderness, Mane said. "Even without war, even if you found a space not already cultivated, you would be forced to occupy a region, delineated in space, time, and energy flow, already exploited by another portion of the ecology."
It took some time for Emma to figure that out. "Yes," she said. "There is bound to be some environmental impact. But—"
"Other species would find reduced living space. Diversity would fall. And so it would go on. Soon the world would be covered from pole to pole by humans, fighting over the diminishing resources.

But Parz was better than nothing: it offered stability, regulation, a framework to live in. People gripe about their tithes—and nobody's going to pretend that the Committee gets it right all the time—but most of us would prefer taxes to living wild. With all respect to you, my friend." He bit into his cake. "And that's still true today; as true as it ever was.

A lion takes only the last deer in the herd. She does not dream of having so many cubs that the plains would be full of nothing but lions. There are simple laws. Most species figure them out; you are the exception. An ecology of a single species is not viable. A diverse, stable world would provide for you.