"I wrote a book once, titled Heads In The Sand. I both own physical copies of the book and own the copyright to the content of the book. It is obviously not equally harmful to me if you break into my house and steal my physical copy of the book than if you were to somehow go to the library and make a photocopy of the book. The difference, not at all subtle, is that when you steal something of mine (be it my book, my iPad, my shoes, my money, my immersion blender or whatever), I don’t have it anymore. If you copy something that you’re not allowed to copy without my permission, that’s a very different issue. Perhaps you deprive me of income I would have had if you hadn’t done that, or perhaps you don’t deprive me of anything. As I’ve said before, I sometimes beg online for someone to send me a copy of an academic article that I can’t get free access to. It’s never the case that my fallback option in this situation is to purchase an extremely expensive academic journal subscription. Nobody is harmed when this sort of copying occurs, and even in the cases where there is a harm the nature of the harm is quite different from the harm incurred in actual cases of theft.
"I’m not really sure why the people charged with enforcing copyright law are obsessed with obscuring this fact. . . . The regulations against copying are supposed to 'promote the Progress of Science and useful Arts, by securing for limited Times to Authors and Inventors the exclusive Right to their respective Writings and Discoveries.' That’s a good reason to have a set of rules, but it’s a reason that has nothing to do with 'stealing.' The question is whether the rules we currently have are actually good ways to achieve this goal."
We had this discussion here a few months ago.