Amazon has and always will make more money providing services to 3rd party sellers and not buying and selling their own inventory of goods. While building Amazon brands is a focus, the much larger focus is increasing the size of the product offering through 3rd party sellers using Amazon for logisitics and selling. eMarketer is projecting Amazon 3rd Party or Marketplace Ecommerce sales to account for $229 billion in the year 2019.
That total will equate for 70% of the overall US annual 2019 Ecommerce sales. That is up from 64% in 2017. Amazon continues to shift to the eBay/Alibaba services marketplace model despite the media focus on private label/Amazon brand offerings. There is a lot more money in being the platform rather than the owner of inventory.