Earlier quoted context omitted.
Why would 1 unit of this game have a "profit margin" of 10%? It's a video game. He's not selling canned goods.
Besides tax and the store's cut, the games also regularly sales and prices-changes. So you can't just extrapolate the price today with the amount of units sold and assume this to be the revenue.
Who did that?
This thread seems to be filled with people who don't understand what marginal cost is.