Being an author is tough, but it's not all bad news. I've made over $2mil over the past 5 years with a self-published book. Certainly not a typical result, but I want to give the authors here some hope.
Self-publishing as discussed elsewhere, is certainly the way to go, otherwise those profits would have gone to the publishers.
I've published three non-fiction books. The first was self published and got noticed by Entrepreneur press. They published the second two.
Despite being a bestseller in the business category, I've made probably only about $30,000 from them. I've been told that mine is also an atypical result as most authors make next to nothing.
Despite having plenty of things to write about, I've since decided there are much better uses for my time.
Distribution on Amazon KDP and ACX (Audible).
The $2m is from book royalties. It has also generated multiples of this in consulting, coaching and course sales.