For first few years, Kindle Reader was a massive sink hole at multiple levels. There was this humongous R&D cost, hardware and software. On a recurring basis Amazon absorbed cellular data charges. Remember this was in early 2008 so cellular data charges were big and since this was the first couple of iterations of product the data sync protocol was yet to be optimised so data intensive. For example, the device would phone home every hour or so to fetch new book purchases and metadata such as bookmarks, last read pages etc., It also included a basic web browser. And finally, the unit economics of selling digital books were terrible. Because Amazon was trying to create a new habit they had to incentivise readers with discounts, even without discount they were losing about 4$/book sold.
So all in all this all seemed like a giant resource consuming operation with no hope of generating any profit. But boy did it succeed. Within about 4 years or so kindle books were outselling physical copies something like 3-1. And now I think it's not even worth comparing.
My suspicion is execs expected Alexa ecosystem to follow Kindle's trajectory of success which doesn't seem to have materialised.