Do you want the long or the short answer?
The short answer is: Priorities and distribution of wealth. Look around at the world and look at the poverty, schools, public infrastructure, homelessness etc. I live in a community that is having a hard time finding Fire Fighters, because we can't afford to pay them more than the going rate of $45K/year. These are men and women who pull you or I out of a burning house.
The long answer would include the economics of the NFL.
People tend to want to think the NFL operates in its own bubble and what happens there doesn't directly affect the economy of others, especially those who don't watch or buy a ticket to a game. Well, how do you think FOX, NBC, ESPN, NFL Network, etc make their money to pay the NFL to broadcast the games? They sell advertisement space. How do the advertisers pay for that privilege? They charge more for their products. So that State Farm Policy you just bought to protect your home cost you $1200/year instead of $900, whether you watch football or not.
So much more to it, but the long and short for me is that the NFL has become a guilty pleasure for me. I see it as an entertainment business that grossly overpays the relatively few participants. Why do they grossly overpay? Because the money is there. To me, the NFL is like a HUGE lottery, where everyone plays, but only a few are guaranteed to participate in the payouts.