The idea that Amazon will pose an actual threat to Google (audience breadth) or FB (audience granularity) is nuts. Just how I'm sure Apple also really felt it when Amazon released the Fire Phone.
Of course it's a threat. Any company in this situation can shift part of their online advertising budget to Amazon, at the expense of ad dollars that were previously spent on Facebook or Google.
Last year Amazon did $10B in ad sales. That was double the year before. Google did about $130B for the same time period. Doesn't seem nuts to me that Amazon can grow their share of the pie quickly. They are #3 globally now.
For context, AWS did about $25B and everyone raves about how high the margins are there -- I bet the ad margins are better!
https://adage.com/article/digital/amazon-makes-quick-work-ad...