Stealing physical books deprives the owner their right to the book.
Copying a digital book only "deprives" the "owner" a right to control its distribution. It's not nearly the same thing. Whereas ownership of physical items is permanent to ensure society would function, the right to control distribution is a concession we make to authors to allow them to make a profit. In our era, this is so ridiculously abused that it is fine to take back some of it. For example, the author should be entitled to the right of controlling copying if he action intends to distribute copies. If book is out of print because the author decides it is not profitable, then the right should go back to us.
