Amazon's Kindle Unlimited Is a Victim of Its Success in Japan (wsj.com)
You really need to understand the market before you start operating there. Take Amazon's case for instance, which has found itself in the middle of a backlash with publishers in Japan. When Amazon launched its "all-you-can-read-subscription" Kindle Unlimited service in Japan, the company didn't know it would become such a big success. And yet it did. So much so that Amazon had to sharply scale back within weeks of its introduction in the country. Before Amazon introduced the feature in Japan, it partnered with Japanese publishers to offer their popular content, committing to pay them a premium through the end of this year when a customer reads at least 10 percent of a book or other content. It worked -- too well, WSJ reports. From an article: Since it's easy for readers to get through the first 10% of a magazine or photo book in just a few minutes, Amazon quickly found itself on the hook for large payments (Editor's note: the link could be paywalled; alternate source), a person at one publisher said. A person at another publisher said Amazon made an overture for talks in September saying it had hit its budget limit for the payments to publishers and wanted revisions to its contract with the publisher."
Not in this case. It was that Amazon offered the bonus on magazines and books consisting of mainly photos. Easy content for person to quickly go through 10%.
It would be like Amazon getting a deal with Marvel and DC for all comic books. Even if you were just browsing a bunch of series you would like go through 10% of a book before switching to something new.
http://www.e-ink-info.com/6-e-ink-pearl-touch-display-kindle-2011-costs-305
Feel free to spell out another analysis that gives different values, but as much as I don't doubt Amazon is making some money on the Kindle, I don't think their margins are nearly as good as you imply.