It depends on where you think ownership comes from.
If you use the Lockean concept where use is applied to create ownership, piracy is fine. Put into an analogy, it's like this: you plant an apple tree. You do not eat the apples from this tree, and they fall to the ground in a public space. Walking over, I pick up and eat one of the apples. I have not diminished your utility from the tree as the apple would have spoiled.
Did I steal from you? It was originally your use that planted the tree, but you don't currently use all of the apples. You are deprived of nothing, and I am momentarily enriched by the consumption. How is that wrong?
If you use the Lockean concept where use is applied to create ownership, piracy is fine. Put into an analogy, it's like this: you plant an apple tree. You do not eat the apples from this tree, and they fall to the ground in a public space. Walking over, I pick up and eat one of the apples. I have not diminished your utility from the tree as the apple would have spoiled.
Did I steal from you? It was originally your use that planted the tree, but you don't currently use all of the apples. You are deprived of nothing, and I am momentarily enriched by the consumption. How is that wrong?