too many people, not enough jobs. Too many people breeding and abandonning kids who growing up will become social rejects who wont contribute and who will be a burden for the specie, who will parasite it instead of contributing. Too many people on earth, not enough ressources. You do the math. We are the edge. It's cyclical. With globalization cynical elites opened the borders so the third world poor classes can compete with western lower and middle classes. As a result salaries are lower, competition is higher... And elites, industrials, politicians and journalists, actors etc can make more benefits.
Nature always find a way to balance things.