While filmmakers and studios would like that logic to be true, since DVDs offer plusher profit margins than downloads, it just isn't.
TV was a tiny business when it started -- so tiny that it couldn't afford to pay enough money for the rights to air Hollywood movies... so Hollywood studios dismissed the medium and refused to sell to it. Home video was a tiny business when it started -- literally, one guy in Detroit (Andre Blay) asking the studios for the rights to sell their movies on Betamax and VHS. It eventually got bigger.
Patterns like this tend to repeat. Online sales and rentals of movies and TV shows today represent 0.5 percent of American consumer spending on movies and television, according to NPD Group. Tiny. But it'll change.