Outside cost of launch I have understood that scaling it to sufficient power envelope with needed cooling is biggest step which most likely makes it unreasonable at scale. That is being able to use enough power to get reasonable amount of compute. Scale it small and low power enough and it is pretty simple. But at that point you might not be talking about amount of compute you expect.

Especially fun when you consider how often gigawatts are talked about with AI. And what that would mean just for cooling as in area... Or then dividing that to sufficient number of individual satellites...