[sathyabhat]

Rich is relative - I've written two books for a publisher and a co-authorship of a self-published book. In both cases, it was nowhere enough to recover the time spent on it. However, seeing the sales figures, seeing your work cited in publications and the reactions you get from people when they say "Oh you wrote that?" - that is another feeling by itself.

You have to remember that a lot of these books are written as groundwork for future plans - far easier to establish credentials saying "yeah I've written that book, you may have heard of it".