With bottled water, I want to count all the costs to the manufacturer of making a specific bottle: materials, wages, property taxes, equipment wear, etc.
With digital content, I want to count all the costs to the manufacturer of making a specific copy: none.
I'm not saying that unlimited copying of work is fair, I'm just saying that there is a qualitative difference in scarcity.
I don't really want to argue about what hurts more. I'll just point out that using nothing, or purchasing a license to work A, or purchasing a license to work B, can all be looked at as causing the creators of A and/or B to forego revenue.