And while fictional evidence is still only fiction, the way that book ends strongly hints that they got something crucial wrong.
They weren't running "on dust", they were running in the simulation of some being that's particularly interested in universes that embed simulations of sapient beings. Such as their own, and then later the "experiment"...
This is similar to the premise behind the novel Permutation City, except that it’s not just one brain, but an entire virtual world.