My rough calculation is that Minecraft goes for 15 Euros, so if he's registering 30k people/day, that's 450k/day in revenue. That's a lot. Maybe it could be double that if people who are pirating the game didn't have that option. But my point is, 450k/day or 900k/day? I'd be happy with either.

EDIT: Sorry, 30k/day is registered and 30% purchased, so it's actually 9k/day roughly. That's still 135k/day or 270k/day. Still, two numbers I'd be fine with.