This topic is close to my heart also, which prompted me to write and query a little further on the topic.
Books are no different a widget than anything else that is sold.
Professional writers market, then write. This is just a sampling of the questions one might ask themselves before they contemplate self publishing. It's a business, just like any other that requires research and insight to be successful. And there are those that are very successful at it, including Dan Poynter and Tom and Marion Ross to name a few. Naysayers abound, Mr. Hunt.