A year ago today, The Worst President in History: The Legacy of Barack Obama was first made available for pre-order. Back then, my coauthor Mark Noonan and I had no idea if the book would sell; we just felt the book had to be written. We couldn’t even imagine that it would become an Amazon bestseller. But, it did!

[image error] Since the book was put up, there hasn’t been a single day without sales. I kept expecting momentum to peter out, but sales continued. Within months, we sold the audio rights to an...