Critics argue that Amazon’s retail business actually operates at razor thin margins or even at a loss when you separate it from the high-margin cloud computing and advertising businesses.
Amazon’s retail operation has massive costs associated with operating fulfillment centers, paying employees, shipping products, and storing inventory. The company is also aggressive about minimizing prices to beat competitors. Amazon prioritizes gaining market share and growing revenue over retail profit margins. The retail business is used almost as a loss leader to attract customers to the Amazon ecosystem.
https://finance.yahoo.com/news/amazon-e-commerce-loss-leader-100629983.html
https://www.restonyc.com/does-amazon-run-at-a-loss/