Well, if you're not a copyright advocate then you pretty much believe that the cost of music ought to be the marginal cost of duplicating it (i.e. as close to z

Well, if you're not a copyright advocate then you pretty much believe that the cost of music ought to be the marginal cost of duplicating it (i.e. as close to zero as makes no difference). If you think it should be higher then you _do_ support the right of the owners of the music to forbid others from copying it (i.e. copyright).