Jeff Bezos knows exactly what he is doing. Amazon is, at its core, an infrastructure company, much like your plumbing or your electricity, except it's one level above those. It's major offerings are infrastructure for web services, infrastructure for shopping fulfillment, infrastructure for digital publishing, and probably a few others. Sure, it is willing to make money by using its own infrastructure to sell you books, shoes, and industrial supplies. In fact, it built the infrastructure to do that, but even if the lion's share of Amazon's profits right now come from selling over the web to consumers, it is not the business that Amazon wants to be in.
Amazon wants you to build a business on top of Amazon where you do the marketing and decide what to sell, but use Amazon's Web Services, Fulfillment, Payments and Digital Delivery to run it.