I’d take the results with a fairly large grain of salt. For one thing, it was an admittedly flawed survey for all the reasons most DIY surveys are flawed. And reading through his observations at the end, some were DOH obvious (no you don’t make money paying for advertising when you’re giving away book free or selling cheap), others were spot on (if you don’t have a marketing plan and keep good records you’re just flinging good money after bad), and some were ‘where the heck did THAT come from’. One observation made was about having a series if you want to make money and again, that’s DOH obvious. Readers love series. They get to stay in a known world with characters they like/love. The survey was unnecessary to understand that.
Probably the most value to be gained from reading this is that one has to do the homework re: advertising/publishing and understand the difference between being a writer and being a publisher.