Not only are they at the top spot, they are ahead by miles in a marathon.
They have almost double the revenue of the next closest sport worldwide, which is MLB or NBA depending on which year as they keep going back and forth.
On top of that, forget the National Pastime, the NFL is the National Obsession.
They are non-stop, all the time without any offseason. It's NFL season 24/7/365. During the NHL, MLB or NBA finals, the NFL is still the most talked about thing in sports.
75 of the top 100 watched shows every year in the US are NFL games and the NFL draft on day 1 averaged more viewers than the NBA and NHL finals and not much less than the World Series.
It's kinda insane actually.