Amazon Marketplace now accounts for $40 billion, or 40 percent, of Amazon’s sales.33 Sellers, content with the massive customer flow, feel no compulsion to invest in retail channels of their own. Meanwhile, Amazon gets the data and can enter any business (begin selling products themselves) the moment a category becomes attractive. So, Amazon, should it choose, can begin offering directly “Old Asian Man Wall Decals,” “Nicolas Cage Pillowcases,” and “55-Gallon Drums of Lube.”

