It's the thrill of the hunt . This is actually two reasons under one heading. Face it, there are just some folks out there who like to live dangerously and walk on the wild side. Apparently, in the minds of these pirates, running OCR software and a scanner is roughly equivalent of a bloody shootout with Federal Agents. This brutal outlaw existence fueled by Jolt cola and doritos is a rather pathetic state of affairs when you think about it.
Guys sucking subway tokens out of turnstiles lead a more exciting life.
The pirate's sole thrill in life is to be the first to put up the scanned version of a book that you can wander down to the library and borrow. In this case, they spend more time processing a book than anyone else will spend enjoying their work. It's kind of a masturbatory existence that produces nothing of value or lasting worth. And, of course, it's ridiculous to assume someone can't be caught. People have been caught and prosecuted, and more will be.