The point: Not that a vast mansion will be too difficult to simulate relative to a smelly hut, but that anything simulated in sufficient detail will become luxury, while non-wealthy ems live in the relative squalor of palatial mansions that just don't look/feel/sound/smell quite right, in an unpleasant way.
Yes, anything is expensive to sim in very high detail. But it isn't at all clear that in typical settings the amount of detail you can get for say 0.1% of the cost of running a brain is usually unpleasant or disturbing.
Lecture at youtube.
Sorry - haven't watched it yet so no summary, but I expect it to be fun.