What is the correct population to have?
Having grown up in a thinly populated area and spent most of my adult life in a heavily populated area, I think that fewer is better.
>>What is the correct population to have?<<
It’s not a question of “correct population” but rather “sufficient numbers of educated, skilled, productive people to keep civilization going”.
Once you fall below a critical number of those people (and I think our “supply chain” issues are a symptom of that) then things fall apart: too many consumers of stuff, not enough skilled producers.