This is where you are mistaken. If I download a bazillionty songs, and never buy a single CD, the RIAA still benefits. Think of the Costco free-food samples. You try the frozen pizza, in fact you help yourself to 6 pieces, yet do not buy the product. Every weekend, you help yourself to more free samples, and every weekend, you don't buy. But, some day you are with a friend who is planning a party, and you say "Those frozen pizza's tasted pretty good". Your friend, based upon your good word then purchases 1 or more of those pizzas. The free samples result in your word-of-mouth advertizing, which is the highest goal that marketing strives for.
You're missing my point. Aside from the economics of the situation, I'm saying that it is morally wrong for people to download music they haven't paid for. As I've pointed out, I don't have much of a problem for people who use it for sampling stuff, but even that is morally tenuous because they are doing so without the permission of the copyright holder (who, IMO, needs to re-think that position in the first place.
Your analogy breaks down quickly because in the case you describe, Costco is providing the samples themselves, as a free sample or loss-leader. A more accurate example would be someone helping themselves (without permission) to free samples by opening boxes and taking a bite -- some of them will buy, but you could hardly justify their actions.
Let the owners of the intellectual property decide.