Amazon's core business is retail, not technology. I am excluding AWS, Mechanical Turk, etc. in this discussion. So selling the Kindle at a loss makes sense to t

Amazon's core business is retail, not technology. I am excluding AWS, Mechanical Turk, etc. in this discussion. So selling the Kindle at a loss makes sense to them given that it will used by consumers to purchase retail goods (books, movies, music, etc. in the case of Kindle). Microsoft's core business is Windows - what would they sell if they give it away for free? Tetris?