Interesting stuff. Thanks for sharing. Setting aside his consulting practice and the net income associated with that, I was impressed with the growth his audiobook income and affiliate royalties. They combined to offset softness in his ebook sales (predominately because it appears he didn't publish in 2018, or was less aggressive in publishing). Yet, I was more impressed by his efficiency in advertising, though it does seem he was helped by an extensive backlist and a strong media presence leading into 2018. One wonders how long he could have sustained that efficiency into 2019 without resurfacing to publish.
Still, the dude is a strategic thinker with a clear plan and the savvy to execute it. Hat tip.