They're not buying homes, new cars, clothing, vacation packages, cosmetics, and hair products.
They also have talent and are likely to critique the hell out of your show, forcing you to hire real talent for actors, writers, the props departments, etc.
The advertisers are better off targeting divorced women or never-been-married welfare queens, with a reality television show using idiotic scripts, non-union actors, and non-union writers.
It's the fast food model versus a family owned steakhouse.
Even worse, over the last ten or fifteen years, science fiction has gone woke, alienating a substantial slice of their traditional young male following.