$50 earned is yours to spend on anything. A $50 discount is offered by a vendor to entice you to spend enough of your money on them to make the discount worthwhile.
Pirates don’t pirate because they’re trying to save money on something they would have bought otherwise… typically they pirate because the amount they consume would bankrupt them if they purchased it through legitimate means, so they would never have been a paying customer in the first place.
So, if they wouldn’t have bought it anyway, and they’re not reselling it, did they really harm the vendor? Whether they pirated it or not, it wouldn’t affect the vendor either way.
That’s not really the same thing, in my opinion.
If you were able to pay for everything handily but pirated anyway, or if you resold pirated content, then yeah you have something similar to theft going on. But that’s not really the norm; those people are doing something bad irrespective of the piracy itself, aren’t they?