David Stinson

I'd say this is a partial misunderstanding, because the difference between final and intermediate consumption is about intention, rather than the type of goods. 

Or to be more concrete, this is where I get off the train.

Would the economy collapse if all humans put their spending cash towards ambitious projects like rocket ships, instead of movies and fast cars? No, of course not! Right?

It depends entirely on whether these endeavors were originally thought to be profitable. If you were spending your own money, with no thought of financial returns, then ... (read more)

If a human population gradually grows (say, by birth or immigration), then demand for pretty much every product increases, and production of pretty much every product increases, and pretty much every product becomes less expensive via experience curves / economies of scale / R&D.

Agree?

QUESTION: How is that fact compatible with Say’s Law?

If you write down an answer, then I will take the text of your answer but replace the word “humans” with “AGIs” everywhere, and bam, that’s basically my answer to your question!  :)  (after some minor addition