Because it doesn't cost them anything? This is so painfully obvious.How is there no direct loss to them when people are playing their game without paying for it like they are supposed to?
You say that it's not theft because it's a copy of something. So if I go rob 50,000 books from a Barnes & Noble, that's not theft, right? Cause, after all, they are simply copies of the book. In order to steal the book, according to your logic, I would have to go find the original copy that the author gives the publisher.
Uhm what? No. If you go to B&N and steal 50,000 books, you are taking 50,000 physical artifacts and depriving B&N of the same. If you go pirate 50,000 books you are creating 50,000 copies and depriving nobody of anything. If you snuck into B&N late and night and photocopied those 50,000 books, then put the originals back on the shelf and took your copies, you would be guilty of B&E and copyright infringement, not theft. That's what's happening here.
Copyright covers the text, or the image, or the sounds involved. Theft covers the book, or the photograph, or the CD. They are completely different and not even remotely related.