I think you need to go back up and carefully read from my first post. I'm not talking about competitive markets in general, I'm talking about a specific transaction where you end up with a product I'm selling, but I don't end up with the revenue I was asking for that product.

As an exercise: walk into Best Buy and pick up a $1,000 TV. On the way out, hand the cashier a check for the wholesale price of that TV. Have you just committed theft? And if so, what specifically have you stolen? You haven't deprived them of the TV itself, since you reimbursed them fully for that.