While your math adds up, I still can't get past the logic. Is the movie somehow worse if it's viewed two months later? $2
Worse, no, but it's also not topical. Part of the experience of seeing a movie when it premieres is being part of the buzz surrounding the discussion of the film. Humans are a social animal (realizing this is slashdot, I feel this must be pointed out), and sharing experiences - such as books or entertainment - is part of the enjoyment of the entertainment.
So, no, the movie is no worse, but the overall experience is diminished. For a second weekend showing, I'd be in for $30, maybe even $50, for a blockbuster. For a third to fifth weekend - most of the social shine is off of it so, no. Granted, I have a 125" screen and a nice sound system so I lose very little watching movies at home but it's still fun to go "out" with the family to see something brand new.