Earlier quoted context omitted.
What really is the issue? That Amazon is leveraging its success to be successful? It's unfair that Amazon is able to see that a product category is doing well so it invests its own money into manufacturing a product to sell through its site? Do you really think that if Amazon couldn't use the data from its own site that it wouldn't procure it elsewhere? Before any product is developed there is extensive market resear…
It is not illegal to have a monopoly; but it is illegal to use a monopoly you have in one area to get an unfair advantage in another. Amazon may or may not legally be a retail monopoly - I do not know the answer. But your question can be rephrased for any monopoly and the answer would be “monopolies should be punished for leveraging their monopoly power in other markets, because that ruins the market for everyone els…
This is a very common misconception in the United States. It’s how a lot of defenders of antitrust law want antitrust law to work, but it is not how antitrust law does work.
This Supreme Court case explicitly establishes that antitrust laws can be used against companies which obtain a high market share simply by anticipating future demand and responding effectively and efficiently.