There's a net new 80 million people added to the world every year.
It's already crowded af in large cities with ridiculous traffic, housing prices, crime, and air pollution (think LA, NYC, Hong Kong).
How much worse will it get before we start seeing a lack of food, energy, and resources (ie. metals) to sustain the population?
This is why Thanos' plan was retarded. He'd only be setting us back to 1970s level pupulation.
Never watched that movie.