In part 3 of his latest thought provoking and entertaining conversation with the Sports Guy Bill Simmons, author Malcolm Gladwell summarizes his thoughts on why (American) football has "been ruined for [him]" and "increasingly of the opinion that it is screwed up -- on a moral level -- in a way that no other professional sport is."
Think about it. The league has a salary cap (which limits players' pay), minimal health insurance for retirees and no guaranteed contracts. In other words, the owners reserve the right to limit the pool of money available to players, to walk away from contracts whenever they please and then hold no long-term responsibility for the health of the players whose contracts they have limited and declined to honor. Coal miners aren't treated this badly. And now we strongly suspect a fourth fact: that some significant percentage of ex-players, as a direct result of playing professional football, will suffer from dementia in their 40s and 50s, in addition to all the known and significant other health risks of the game (severe arthritis, substantially elevated risk of heart disease, etc.).