Uh, we are already past resource tipping points as human beings. This means we use more resources than the Earth is producing in a single year, which also means we cut into the resources that have been generated in other plentiful years (like old growth forests, fish populations, etc). If we efficiently utilized the space we have we could raise the bar for that resource tipping point, but we don't.

So yeah. TL;DR: it's not necessarily that we're overpopulated now but our population size + overconsumption = effective overpopulation.