My father wrote a book. It was about the life, and ultimately, death, of my younger sister, Elizabeth. He tried to get it published, but was rejected. "Too personal", they said. So following his death in 2008, I paid to have it published at an on-demand publisher - that is one that the author pays for, and the publisher only prints when they have orders. That keeps the costs down, and allows very small runs.
I doubt this will ever be a best seller, but any money it makes will go to leukemia research.