Good points- piracy is positively correlated with sales.

Now for books- it's a different industry but in the end piracy is still correlated with greater exposure, which is gonna mean sales. There were even some stories earlier this year of authors illegally uploading their own books, in hopes of greater exposure. Found one, it's linked.

In terms of pirating books, I think the most common scenario is a person who already supports the author and owns the physical book (possibly more than one copy!) but upon getting a e-reader and enjoying the convenience of reading on it, wants to read the book he/she already owns on the ereader. Many people who buy books a lot will have a backlog of books they need to read and they feel like they shouldn't buy books until they've read the books they already own. Now, if it's easier to read the book on the ereader, they'll get through the backlog of books faster and be buying more books sooner. I know it's definitely illegal but I don't think it's wrong to download an ebook version of a book you already own.

It's not the kind of thing where you're going to read 1 book a month, regardless of how you obtained it. The more people read, the faster they read and the more they read and the more they anticipate books by their favorite authors and the likelier they are to spend even more money on books. If you discover a new favorite author via piracy and the new book comes out, you've gonna want it immediately or even before that you may want to buy more books by that author, possibly including the book you've already downloaded. People do want to obtain things the "official" way. Even though it's actually easier to download books, somehow getting ebooks from public libraries is very popular. (To the extent that publishers are freaking out about it!)