That's what sukilot said: it is a fallacy to assume that people would pay for content that they can't pirate. In actuality, it's the other way around: people pirate content that they can't pay for (either because they have no money (at all or in a currency that the publisher accepts), or because the publish refuses to deliver the content (either at all or in a format they can actully use, ie not DRM-encumbered or otherwise defective)).

It seems unlikely to me that piracy is a major factor, as headline-grabbing as it often tends to be. It's hard for me to even hazard a guess how the IA's "emergency library" would really affect things; it's not piracy in any conventional understanding of the term, but maybe that makes it more likely to cost authors potential sales, because it's so easy to read the book for free. But I want to triple underline that maybe and surround it with question marks.