Unfortunately, people want to do more than eat. They want sanitation, energy, entertainment, paper, houses, schools, jobs, transportation, infrastructure. Natural resources are, in some cases, not renewable and they are dwindling.
This is very true and yet, these things tend to be self-sustaining ( jobs for example exist to meet a demand and more people also = more demands). As for natural resources, yes many are not renewable but we those are the ones we need to stop relying on.
This is an old story, as the saying goes, everytime the world heads towards another "population milestone" these discussions come up and the fact is, the issue is NOT global population but population density in specfifc areas.