The phrase “a fraction” in Bostrom’s setup means a small portion, meaning it wouldn’t need large scale planning and agreement across the civilization to use it.

The phrase “a fraction” in Bostrom’s setup means a small portion, meaning it wouldn’t need large scale planning and agreement across the civilization to use it. Any rando could do it. And in general, randos aren’t bound by notions of rationality. Some would launch simulations just because they could, or for no reason at all. I still think the setup is such an enormous assumption as to beg the entire question.