The few thinkers have long realised that 8 billion is probably 7 billion too many.
There is NO planet B.

8 billion is probably 7.9 billion too many.

The author only touched on the economical aspects of overpopulation, and one billion people could possibly dodge it and survive from a solely economic point of view for some centuries, but what about the social consequences?

Once human population exceeds 100-200 millions, there is no choice but to limit their steps so they do not step on each others' toes: governments, laws and regulations must be brought in to manage the increasing numbers and people are no longer able to just move out to the next valley if they find them unacceptable, because the next valley is no less densely populated.

Then once population exceeds about a billion, while physical survival may still be possible, people can no longer be left out without names, surnames, identifying numbers, nationalities, passports, licenses, tax and welfare records, credit ratings, etc., etc., etc. People then are no longer allowed to support themselves and must be regimented and stacked up in straight rows, columns and layers: Yes, they may technically survive, but are their lives still meaningful and worthwhile?

The dead and the unborn do not sense the passage of time, nor feel boredom, so why the rush to bring them all in at the same time?

Resources on Planet Earth can sustain much more than 8 billion humans.
Ecosystems can be regenerated while developing viable businesses and employment.

Most non-renewable resources following use can be recycled or conserved.

The most significant handicap is the daily shortage of affordable nutritious food. Eight billion people and their animals need essential amino-acid-linked proteins daily.

Authorities decided aquaculture would supply world demand for fish but ocean fish stocks are already so depleted there are not enough oily fish to feed aquaculture.

Demand for scientific evidence of fish depletion before action is taken is preposterous. Original fish numbers were never counted and its impossible to count wild fish that presently remain.

However humans are clever and can overcome sewage point source nutrient overload that is proliferating algae that is destroying ocean food-web nursery ecosystems.
The fundamental problem is not overfishing or CO2 or plastic.

Nothing sensible is impossible