Full disclosure: I work for Hodder, the publishers of The Violent Century, but I'm commenting in a purely personal capacity.
To clarify, the ebook is cheaper than the current physical edition, which is the hardback. The paperback is only available for pre-order and isn't published until March. Amazon.com isn't listing the hardback as the main edition, for some reason, which gives a misleading impression.
The price of the ebook will drop when the paperback is released. "Windowing" ebook prices to reflect the price of the most current physical edition is common practice for publishers. Whether that's a fair strategy is another question. But it's quite simply not the case that the ebook costs more than the physical book.
It's up to you to decide if you want to part with your money for it, of course. But The Violent Century is a really great read - Lavie Tidhar's writing is brilliant, so I hope you'll want to check it out!