It's all of the above.
The NFL did a great job of locking in the hard core viewer and luring in the casual fan. You push push push on fans and eventually you push them out.
The core football fans will put up with almost everything - ticket prices, idiot players, dumb penalties, terrible guys/gals calling the game, hideous online coverage, bad leadership/decisions by the league, etc. However the casual fan can break away easier and find something else to do.
The anthem thing is damaging and it's not even about that actual act but within that act is a disdain for the fans/customer. The owners and commissioner quickly recognized this and are trying to put a stop to it but the players want it. They are mad that they aren't allowed to upset the customer and just don't get it. What Sterling Sharpe and Greg Jennings said last night was absolutely ignorant. They literally cannot understand how the fans are linked in this.