Digital scenario (legal, with DRM): I pay you $10 and you issue me a digital copy of the book, on terms that you can change at will. If you go out of business, I lose the book. If it turns out that you messed up your upstream licensing, I lose the book. If the book is banned by your government, I lose the book. If you decide to discontinue the service for business reasons, I lose the book. In some cases, if my computer breaks or if I upgrade it, I lose the book — at least until I spend an hour on the phone with your tech support convincing them to give it back to me.