They might not sell at full retail price, but eventually they do get sold, retailers don't just trash games if they don't sell at $60, they drop the price until they are sold. There might not be 1.2 million people willing to buy it at $60, but there are 1.2 million people who will buy it, the question is how much do retailers have to drop the price to get the rest of the inventory sold, and how long will it continue to sell decently at $60 causing them to order additional copies raising the shipped number.
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They might not sell at full retail price, but eventually they do get sold, retailers don't just trash games if they don't sell at $60, they drop the price until they are sold. There might not be 1.2 million people willing to buy it at $60, but there are 1.2 million people who will buy it, the question is how much do retailers have to drop the price to get the rest of the inventory sold, and how long will it continue to sell decently at $60 causing them to order additional copies raising the shipped number.