I don't know where people are getting the idea that 1 million copies sitting on shelves is too much.
If anything, I'd say it's too little. There have been several calculations showing that hardware sitting on shelves is around 1 million (usually a bit less). It's not surprising at all to have games at the same or higher level.
Also, notice that it's not just copies sitting on shelves. There are also copies at warehouses and in shipment (i.e. sitting on ships or trucks).
My Mario Kart Wii friend code: 2707-1866-0957