“Right now, Earth’s carrying capacity is thought to be somewhere in the range of 4 billion to 5 billion people.
There are 6.5 billion of us.”
The Earth’s land surface is 148,939,100 km². If we were all still Palaeolithic hunter-gatherers, we would need at least 10 km² per person. So the carrying capacity of Planet Earth was at most 14,893,910 people using hunting and gathering technology.
Technology doesn’t remain constant.