As mentioned before, it's advertising. The more highly rated a show is, be it sport, or any other type of show, and the more people that will be tuned in, then all those ads and commercials you see is what pays a very large portion of profits. Air time for commercials go for hundreds of thousands of dollars, even millions in some cases, and that's for one single commercial. Wonder why name brand products cost more? Because they advertise! And we the consumer absorb the cost.
