I had no idea Amazon advertising could be so profitable it could out-earn its retail business but looking into it it makes sense. Amazon search results by keyword has to be the most effective form of advertising I'm aware of. Google searches, social media ads, TV ads, etc., are mostly just throwing up noise. But when I search on Amazon, similar to how I used to search eBay, those promoted results are relevant to something I'm actively looking to buy. And since Amazon is my go-to retailer for nearly all non-basic necessities, it's probably the most relevant and targeted advertising I see by far.