They stole from the amount they would have legally paid to buy a copy from the copyright holder.
Think about it like sneaking into a movie theater and watch a movie without paying. The theater was going to play the movie anyway and, assuming it wasn't a packed theatre, I didn't deprive anyone else of their ability to watch. It's still theft because I'm getting something that costs money for free and depriving the theater of the money that they're owed.
Think about it like sneaking into a movie theater and watch a movie without paying. The theater was going to play the movie anyway and, assuming it wasn't a packed theatre, I didn't deprive anyone else of their ability to watch. It's still theft because I'm getting something that costs money for free and depriving the theater of the money that they're owed.