This is strange as economists agree pretty much across the board that one way of making an economy grow is to increase population. It stands to reason that one way to shrink an economy is to decrease population.
Note that I am making no comment how that growth or shrinkage affects the quality of life in that economy but when looking at total growth population change is correlated.
To take it to extremes - just to prove that overpopulation can lower output, imagine our population increased 1000x overnight, do you think in this scenario the economy will grow? I imagine this situation would not be handleable and people would be going completely crazy killing each other.
The above scenario is not realistic, but what about if population grows and grows and then comes a point where we realize that for example we have
1) Reduced potential living space by a huge margin due to for example climate change or pollution.
2) We have no idea how to solve this issue. We can't move to another planet, we don't have the tech yet even if this was possible.
There's many potential ways we could fuck up which causes there to be limited basic resources that at the very least would make the world scramble to solve this issue and produce less value because they have to focus solely on this issue and large proportion of people would have to be fending for themselves, with sometimes only options to get basic necessities is to steal from others.
Or the people who are rich, thanks to using the monopoly principles will be good because they have enough money, power and control to buy the remaining resources.
I mean yes, that's what I said. It might or might not happen. But it's just a scenario where it will be a zero-sum game or less. I'm not saying it will happen, just that it is possible.
