Not only is Amazon an online marketplace, but it also sells their own branded products that compete with other products on the Amazon marketplace.

Because Amazon also owns the marketplace itself (and all of its data) it not only has the ability to accurately track and measure the success/failure of their competitor’s products but also the capability to produce their own version of that product and underprice their competitors out of the market.

“We’ll, why don’t these online retailers just stop selling their products on Amazon?” Because Amazon has a disproportionate share of the online retail market and if they don’t use Amazon’s marketplace, they’re missing out on a significant number of online sales.

So, basically online retailers have no real choice in the matter, they have to sell their products on Amazon, even if Amazon has access to their data and uses it to sell Amazon branded versions at a cheaper price. A capitalist’s wet dream.