Noting people do is 100% optimal, but productivity gains mean resource constraint problems are more solvable than they first appear.

People are worried about automation driving people out of the workplace while others are worried about a lack of workers due to changing demographics. What’s going to happen is the result of a bunch of different forces, simplified projections are easy to make and unlikely to prove accurate.

It is insane that people think we need a growing population to make this perfect population pyramid, to make things work easily in monetary terms with taxes. It really does ignore so many of the other forces as you mention.

The picture looks radically different if you focus on real resources and allocation. In fact a growing population could make things very economically tenuous in real terms, depending on how a few key environmental factors play out over the coming centuries.