Liveable necessities like water, food, and housing, that are either wasted on inefficient food production methods or given to rent-seekers (by the economic definition of the term). No one is claiming we are post-scarcity and that everyone can have the standard of living of a millionaire, though I would argue that one having a standard of living like this could take away from other people's standard of living.

Basically my argument, since this thread is quite far down now, is that over-population is not robbing the globe of resources in any amount worth worrying about and therefore population control is not going to solve inequality since it's a distribution problem.