The basis of our economic system is our right to sell our products in the way we see fit. Thus, content providers have the right to put any DRM system they want on their products. If we don't like DRM, then we simply shouldn't buy those products.
We don't have any right to pirate content, because piracy is theft: for any pirated product in use, the creator is missing a certain amount of money.
The argument "a pirated product is not a lost sale" is a bad argument, because it is a tautology: "a lost sale is a lost sale".