It's not about decreasing how much each person has - quite the opposite, actually. It's about increasing the efficiency of how we distribute our resources so that more gets to those who need it because we already have far more than we need but most of it is wasted or artificially made scarce to increase profit.

The US throws away something like 60% of the food we produce annually while kids starve and politicians talk about getting rid of free lunches at schools.

The "overpopulation" fear is really just misdirection from the greedy few to keep the rest of us from questioning why we let them get away with everything.