First of all, I'm sure the actual original copy actually has more value for collectors and the like.

The real argument is that they are just copies and literally cost the studios nothing--that is, the studios do not have to spend any money on your downloading the film from a third party. So, by extension, you pay them in a way that does not cost you anything, by using a copy of money.

The only value a copy--distinct from the media its on and the bandwidth it takes--is through copyright. If you do not believe in copyright, or at least not in the system as is, (and I imagine the person who set this up does not) then these copies do not really have value. The analogy is to the smell from a restaurant--it costs the restaurant nothing, so if somebody outside enjoys it, they do not have to pay the restaurant anything.