Nice strawman, mr. ignorant. What you described isn't the current reality; fantasy situations are not useful to debate here.

I gave an exaggerated example so that the dimwitted could understand something that apparently isn't clear: not everyone in a population counts equally. Only the smaller fraction of a population that is capable of reproduction counts.

It's not 8 billion in number, and in most of the world it is shrinking.

A subset of 8 billion is sufficient as well.

Really depends on the subset, doesn't it? In Japan and China (even Poland, recently), that subset is so small that the population is shrinking year-to-year. Annual deaths outnumber annual births.

It's quite clearly getting ready to happen pretty much everywhere else, and is masked by immigration in those places where you might claim that population isn't shrinking.

All I see is ruinous insufficiency.