I tend to agree with you, but I think it's a little more nuanced. Widespread copyright infringement causes those who would otherwise purchase to not purchase, which DOES deprive the copyright owner of money. There's no reason to believe all pirated IP could have been a potential purchase, but even if 1% or 2% of it was, and I'd wager to say that this figure is much higher, that's a significant amount of money.
Of course, there's also the argument that piracy increases music discovery and perhaps is a form of fair use (as a backup, alternative to a streaming service you purchase, etc), which might drive revenue in other ways. I have yet to find or hear of any substantial empirical evidence for this, though.
EDIT: by the way, I think the best way to argue this is that you are never actually given ownership of any IP, only a LICENSE to use it, therefore you are simply violating the license agreement.
Of course, there's also the argument that piracy increases music discovery and perhaps is a form of fair use (as a backup, alternative to a streaming service you purchase, etc), which might drive revenue in other ways. I have yet to find or hear of any substantial empirical evidence for this, though.
EDIT: by the way, I think the best way to argue this is that you are never actually given ownership of any IP, only a LICENSE to use it, therefore you are simply violating the license agreement.