Check Amazon’s Antitrust Paradox by Lina Khan (FTC). A very detailed review of how Amazon is a monopoly and how they dodge antitrust legislation.

That’s not how it works. Or, rather, that’s not only how it works. Sure, advertisers dream of users who see an ad once and run to buy a product. But ad effects are spread over time. They build brand recognition. They fake familiarity. Say you are in a supermarket and you want to buy a new type of product that you haven’t bought before. Very likely you’ll pick something familiar-sounding, which you heard in an ad. Ads pollute the mind even if the most obvious effects are, well, obvious and easily discarded, more subtle influence remains.