You can't compare a download price to an actual physical copy. The main point being you physically actually do not have anything when you purchase on download it really is totally worthless
That's a good point. When you pay for a download you are only buying a licence to listen to the music. Just because downloads no longer have DRM it doesn't mean that you own anything that you can legally sell on. You're effectively only renting the music, even if in practice you can keep it forever.