Also I happily buy lots of books from people like Cory Doctorow and nostarchpress -because- their books are public and I want to support authors that value the freedom of their readers.
Books that are DRM or copyright protected however, I buy used paper copies or pirate because why would I financially support people that do not respect my freedom?
Are you sure they are free?
Look, let's be honest - what gives you or others the right to steal from others?