Ustopia land was a wonderful place. It was rich in resources and generally temperate in climate. It was blessed with about everything that the natural world could provide. Early on there were few natives to enjoy its benefits.
Then, they harnessed the energy and started using up the riches; slowly at first, and then in a ravenous manner without any thought given to their finite quantity.
As a result, their numbers grew without regard to the ability of Ustopia to carry them all to wonderful lives. Soon, Ustopia was not so wonderful anymore, and a malaise came over the land.
“What can we do now that there are no more free or cheap nourishments for our desires?” the leaders said. “Can we find new worlds somewhere with the riches that we had, to exploit? Will we have to live with less of the wonderful things that we created, like our ancestors had to?”
These were questions that they never answered. They started quarreling among themselves, and as the resources diminished and their numbers decreased, the natural world looked more natural again. The citizens are still there. There just aren’t very many of them.