Maybe with Starship the premium is less extreme? $10 million per 350 NVidia systems seems already within margins, and $1M would definitely put it in the range of being a rounding error.
But that's only the Elon style "first principles" calculation. When reality hits it's going to be an engineering nightmare on the scale of nuclear power plants. I wouldn't be surprised if they'd spend a billion just figuring out how to get a datacenter operational in space. And you can build a lot of datacenters on earth for a billion.
If you ask me, this is Elon scamming investors for his own personal goals, which is just the principle of having AI be in space. When AI is in space, there's a chance human derived intelligence will survive an extinction event on earth. That's one of the core motivations of Elon.