I'm sorry for jacking your analogy, but I think it holds water. Diamonds are not inherently valuable (to the degree they are priced at retail). They are valuable because of an exploitative supply chain and social manipulation efforts spanning decades. Which does not justify robbing stores and potentially causing physical or mental harm to innocent shopkeepers. But very much justifies replicating the product to render those practices worthless and hopefully deter them from happening more.
The same goes for educational textbooks in many (but far from all) cases. Personally I've had professors who assigned their own books at very reasonable prices and apologize profusely for them costing money to begin with. I've had others who peddled their own expensive books while themselves handing out copies (!) of books by other authors. I wouldn't dream of pirating the former, but I'm pirating the shit out of the latter if I can.