Why write books? Another form of orgasm?

I remember reading a few years ago (age is catching up--can't recall where I read this!) the author noting that there is a book within every person and most of us need to know how to make sure the book stays there and never comes out.  Yet, people write books and most of them are awful.

The NY Times' Bill Keller writes (ht):

Writers write them for reasons that usually have a little to do with money and not as much to do with masochism as you might think. There is real satisfaction in a story deeply told, a case richly argued, a puzzle meticulously untangled. (Note the tense. When people say they love writing, they usually mean they love having written.) And it is still a credential, a trophy, a pathway to “Charlie Rose” and “Morning Joe,” to conferences and panels that Build Your Brand, to speaking fees and writing assignments.

Writing books for self-satisfaction seems more like a polite way of how I refer to most of the book writing that is done within the ivory towers: onanism of the intellectual and literary types!  May produce satisfaction and alter oxytocin levels in the person, but that is all.

Speaking of books written by academics, it would be lovely if professors who list books in their vitas also identified in their annual reports how many copies of the book were sold to buyers other than university libraries.  Most academic journal articles are rarely ever read, and I would hypothesize that most academic books are bought only by university libraries, and then the books gather dust on the shelves.

Full disclosure: I have never written a book, and have no plans to write one--at least for now :) 
I have pretty much stopped reading books by academics too.  Most books are nothing but fluff, and if there is a nugget of wisdom in them, well, it would have been published as a journal article a few years prior to the publication of the book itself.  A 15-page essay almost always contains everything that we would want to know from that 300-page book, and I way prefer the 15-pager.  But then most academic journal articles are also crap--nothing but intellectual onanism.

Now, a collection of Calvin and Hobbes cartoons is a book you ought to own :)