They're not putting up just one satellite. It's going to be a constellation. The constellation as a whole will be equivalent to a data center.
Also, it won't cost them millions of dollars to launch a single satellite. That's why this project is paired up with Starship development, the two go hand in hand. Starship makes the launches cheap, Starmind gives Starship the scale of demand a ship like that needs for its economics to work.
2-10 million per launch, but each launch will carry ~60 satellites. So that's as little as $30,000 per satellite.
Starship is going to fundamentally change what the launch industry is. It's easy to overlook.