> Now here is the question: when I copy your song, am I depriving you of anything?

Yes, because there's a chance -- say, 5% -- that you would have bought it. So, you're depriving me of wealth and money.

Buying music, software or any other digital good is a contract, a promise: I promise you a copy of my music, you promise to pay me money and don't copy it for others. If you don't like the conditions of the contract -- fine, buy elsewhere!

But if you agreed to the conditions, violating them is immoral.