It is undeniably true that Amazon has a very large share of the market for e-books. What is not true is that Amazon faces a lack of competition in the digital book market. Barnes & Noble — a company that knows something about books — sells e-books, and does so in partnership with a small outfit called Microsoft. Apple sells e-books and so does Google.
These are not obscure companies. It is not inconvenient for customers to access their products. And since these are companies that are actually much bigger and more profitable than Amazon, there is absolutely no way Jeff Bezos can drive them out of business with predatory pricing.
Amazon’s e-book product is much more popular than its rivals because Amazon got there first, and the competition has not succeeded in producing anything better. But consumers who prefer to buy a digital book from a non-Amazon outlet have several easy options available, and thus a book publisher who chooses to eschew Amazon will not actually be unable to reach customers.
There is more here, a good rant.