Amazon does leverage their position as market maker to undercut competition with anti-competitive practices though. They run data analytics to figure out what goods are the most profitable, then launch competing products and promote their own over the originals in their listings. Their monopoly gives them the ability to take over nearly any market they want at any time, with no consequences.
> They run data analytics to figure out what goods are the most profitable, then launch competing products and promote their own over the originals in their listings.
Figuring out which products have high margins and entering those markets is an increase in competition.
Promoting their own listings is only a problem if the competitors can't reach those customers in any other reasonable way, which isn't the case because there are many other online retailers and it's quite feasible for a medium sized competitor to sell directly to the customer on their own website.
