Earlier quoted context omitted.
There is not enough space for 8 billion humans to do "frontier living."
It always intuitively felt to me like there was enough space, but I am now getting the sense that my intuition here has been wrong. Will you define "frontier living" so I can better see the lack of space ?
Next is amount of people. Current human density is supported by antibiotics. Take away them and we quickly fall back to around 1900 population density (1.6 billion roughly). And not even internal antibiotics, external antibiotics like chlorine for cleaning and water purification.
So those are the setups for population collapse. When population starts collapsing this way it generally overshoots the numbers pruned because of war/disease. We won't fall to 1.6 billion, it's likely to fall well below 1 billion.