After the Super Bowl, there is a bit of a hangover, but then Spring Training, March Madness, Baseball opening season and onto the NBA Playoffs. The NFL only has 16 games a year and that's great, same with college football, but with free agency, the draft & OTA's, there is plenty. The USFL signed some great football players with the likes of Herschel Walker, Steve Young & Reggie White and they still folded.
Even if you don't follow the other sports, you need the downtime, I tried to watch some of the games and there was some exciting football, but other things were priorities, with family, graduations etc...As much as many believe the more football the better, @RockRam is right, too much of a good thing.