Jim, Congratulations! I think you just SINGLED OUT the CORE ISSUE... MONEY!
From OVERSIZED, yet UNEARNED PLAYER BONUSES, to GAMBLING now being openly attached to the game, who needs to worry about MONEY... it's everywhere and part of everything.
Only a very few of the PLAYERS are motivated to perform better. WHY worry about IMPROVING when you got all the MONEY up front in signing BONUSES and GUARANTEES.
The big difference in the NFL vs the other professional sports is the length of time they play. Very few NFL players are in the league for more than ten years. I believe the average is eight. The exception being place kickers and back up QBs. As we also know 50% of NFL players are bankrupt in 5 years after they retire from the league.
So, the reason the NFL owners can afford to pay players more is because the NFL is making so much money as a league. Which is also the reason why they continue to pay Roger Goodell so much money to run the NFL.