The validity of Cory Doctorow's business model

Cory Doctorow is a writer and blogger who writes stories in different magazines and also edits famous weblog Boing Boing. He is known as an activist in liberizing the copyright laws and a proponent of the Creative Commons organization. He is also known by publishing his books in Internet under Creative Commons licenses. His first book published in 2003 under CC was "Down and Out in the Magic Kingdom". Many of he's books are published under NonCommercial + ShareAlike combo license, which means all noncommercial derivatives with author attribution can be distributed under license identical to the work. All of he's novels after 2003 are published with CC license, but all of the licenses are noncommercial.

So where the money comes?

I guess, that Cory Doctorow is using CC noncommercial licensing method to get wide distribution of his books. Along with the mass distribution also comes good notoriety. The idea to allow readers to share the book by themselves is giving him an advantage not to pay for distribution at all. He has gained lot of fame with this method and many people know he's books and review them online, which also affects the sales of hard copy books in bookstores. He is using the most widely spread online strategy in his publishing business, give digitally free and sell hard copies. Most of the money comes from donations and sales of the hard copies all over the Internet.