I never understood the concept of buying movies. How many times can you watch the same damn thing?
Beyond that, I completely agree with you though.
I am surprised, though, by how many times my older kids and my wife can still re-watch the same thing. I think it is comfort with the known; I am much more of a risk taker than they are.
Note: I live in an area which doesn't have Netflix, so I'm comparing to renting from a store/kiosk.
I barely ever watch a movie twice, but I can watch it an indefinite number of times as long as there's at least one person in the group who hasn't seen it.
EDIT: If you think about Shakespeare's tragedies, they are being played by different acting companies for centuries.