I think ya got that backward!
The media wasn't interested in NASCAR but for a couple major races a year. It was sent to the back lot, so to speak. Thanks to Bill France, Jr's marketing genius and the growing number of fans, the media outlets wanted a piece of the action and they grabbed it; and managed to keep it, on France's terms.
In Atlanta alone, the two major racing weekends at Atlanta Motor Speedway brings in more revenue than the entire seasons of the Braves, Hawks and Falcons. You say it's media-driven. I say it's fan-driven.
So... blame your wife!