In the 'west' we consume resources at 32 times the rate of people in the third world. Each one of us consumes in a day the same resources, and creates the same waste, that 32 Indonesians or Kenyans do.
The problem, of course, is that third-world economies are quickly catching up, and the goal for many people in those countries is to reach a 'western' level of consumption. But if the whole world started consuming at our inflated rates, it would be the equivalent to having 72 billion people on the planet at today's consumption rates. And we're having trouble sustaining things as is.
But it's patronizing and insulting to ask those economies to forgo a goal which we already enjoy. So the challenge is really how do we find a way to stabilize worldwide consumption - reducing our consumption to a level to which they can grow. This makes it sound like we need to undertake radical sacrifices, but Diamond points out something important - resource consumption is not really tied to standard of living. Our consumption patterns are so wasteful that we could cut them in half and not notice a difference.