It's copyright infringement, which is not theft, they're legally distinct in the eyes of the law. This is partly why the "you wouldn't download a car" copyright ads were so widely mocked.
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.
It's fine that you think that way. But this is a discusion of the laws of the United States of America and ruling by American courts, not a discussion of your own legal theories.
The GP isn’t talking about some edge case legal dilemma that requires a lawyer or judge to comment. It’s already widely documented that copyright infringement is legally distinct from theft.