Spending $200+ for 2 tickets to sit in the nose bleeds, $20 for parking, and eating no concessions while dealing with the traffic to/from the stadium isn't worth it. Then, throw in the poor quality of the product (I'm not even talking about politics) and there's no reason to waste any time on it.
The NFL is a QB driven league; you have to have a good one to succeed. If you don't have one, there's no point in playing as the rules they've implemented require you to have one. Nothing else matters and there aren't enough good QBs to make it interesting.
I think we're hitting a tipping point with sports and entertainment in that people just aren't willing to spend the money that's required anymore, especially, when you can just watch it on TV and see more and probably have a better experience. Simple economics as the price point is too high for the demand.