It’s a well known fact that textbooks are expensive and that writing a textbook earns you very little in royalties (e.g. https://academia.stackexchange.com/a/167367/11353 ). At the same time self-publishing is becoming a bigger and bigger deal in non-academic circles. This sounds like an ideal solution for academic textbooks.
Are there any examples of popular self published textbooks?
I am not looking for any type of (exhaustive) lists. I am either interested in even a single example of such a textbook or alternatively answers that explore the main issues with this approach. Going through my collection of books from the time when I was ‘in academics’, I cannot find a single book that looks like it wasn’t published through an (academic) publisher.