Everything King Midas touched turned to gold. Amazon has the same touch. However once something's touched it's no longer useful, no matter how bright and shiny it becomes.
Amazon now sells more books than anyone else. They sell other things as well. People visit big box stores to view merchandise and then they buy it from Amazon. This forces retailers to change how they do business. It's change or die. Huge bookseller, Borders, failed to change quickly and went out of business.
Amazon owns the majority of the eBook trade partly because it made it easy for writers to self-publish. This has been a boon to writers, but also an obstacle. They must play Amazon's game or not play at all. Like all games, the odds in this one favors the house rather than the player. Amazon's subsidiary, CreateSpace, makes it easy to publish paperbacks, but provides no path to getting those books into stores. Bookstores don't stock them because CreateSpace doesn't won't allow unsold merchandise to be returned like traditional publishers do. And now those traditional publishers are facing new difficulties.
After hurting traditional publishers and retailors, Amazon has opened its first bookstore in Seattle. Mom and Pop bookstores are already struggling or failing; there's no way they can compete against Amazon's superior data and pricing. Amazon is becoming an invisible monopoly unnoticed by government watchdogs. Today it's only one store, but that could change tomorrow. My advice: Don't shop there. It's a trap.