when a movie is being sold on disk after theatre showings close out, there is already a return for investments and disk sales are just gravy.
disks are played many times lent out to family and friends watched in recap after the theatre and donated to thrift shops. a large group of people can "steal" by watching for free multiple times, but millions have been made in theatre wages paid and investors pacified.
when a movie is cammed this cuts into the revenue.
i believe in a co-existence being possible however thats short circuited by the one "free" view == one lost/stolen sale mentality.