> For it to be worth a trillion dollars it has to take a trillion dollars from somewhere.

Musk's SpaceX TAM is roughly as you say, it's "subsume all currently existing desk jobs", which makes it simultaneously absurdly over-confident in the short term and treating this all as a zero-sum game where those jobs just go away and no new (potentially also automatable) jobs get invented, which in turn says he doesn't think anywhere is going to shift from primary and secondary economies to tertiary economies.

Zuckerberg may be full of himself, but does at least (pay someone else to?) write a vision that at least has growth-sounding phrases in it: https://www.meta.com/superintelligence/