If that's (ahem) true, is it because people who like entertainment other than "Sci Fi" are more willing to pay for it, or simply that there are so many more of them? Neither is much of an argument in favor of sf.
Probably more due to the fact the things nerds like in SF - stories, characterisation, ever romance - aren't what studios want in SF - product placement, viciousness, expansive plastic surgery. I'd pay to see Stephen Fry as a Klingon - they want me to pay to see Will Ferrell as Jim-Luke Packard. It ain't happening
This may (or may not be) good for SF. It's bad for the studios. I have more money to spend than kids & they ain't getting it