Amazon is in the ad-biz and they're already near the top of the pile [0]. They're in the silent data gathering phase. All the data they have from 1) eCommerce 2) device like Firestick/kindle/alexa 3) apps like Audible 4) retail (wholefoods) and all their other operations can be combined (if not already governed by a single privacy policy) to leapfrog any competitor.

As you say, they are not dependent on their ad business, but they are making a lot of money from it. Expanding operations to improve profits is a no-brainer and they can existing distribution networks like AWS to have an extra edge.

[0 ]https://digiday.com/marketing/amazon-ad-revenue-2-2b-132-per...