Sure players knew football was dangerous. That doesn't mean they knew that re entering a game shortly after having a concussion could put you at risk of early onset dementia. Causing you at age forty to forget how to get home from the store.
Did the NFL know the risk? There are certainly allegations
that they did, however this thing never went to trial, thus no liability on the NFL's part was ever proven IIRC. Further, if the NFL had even a small inkling that such risk were present, don't you think at least one NFL player would have been privy to this information? I have serious doubts that all 28, 30, 32 teams colluded to such an extent to keep information from what at this point would have been thousands of players for a time period of over 40 years.
IMO, neither side of the dispute knew the full extent of the potential risk. They couldn't because medical science had not progressed that far at that point in time. The players are essentially arguing that the NFL had a duty to protect the players from themselves from medical risk that have only recently been identified. The question is did the NFL have such a duty? There are countless stories of guys in the 70's, 80's, 90's, 00's that flat out refused to listen to the medical personnel on the sidelines who advised them not to reenter games after they were injured. There has to be some personal accountability for that, doesn't there?
Players aren't suing over bad knees and bad backs
Yet. There is blood in the water, and you can bet that an enterprising plaintiff's attorney will be looking to get a piece of the pie. This whole thing is a plaintiff's lawyers "wet dream" ala the tobacco and asbestos litigation. Enormously wealthy defendant, and many plaintiffs who have squandered much of the fortune they earned in their playing careers.
Should the NFL have some sort of program set up to facilitate the medical needs of its former players once they leave the game? Maybe. But many of these guys made, and are making 6,7 figure yearly salaries. Shouldn't they also bear some responsibility for ensuring that they're inevitable medical needs are taken care of after football?
What's happening slowly, but steadily, is that football as we know it is being litigated out of existence. The NFL is first, but their are already class action suits being filed on behalf of people who played football at the college and High School level. While the NFL may have the funds to settle with or compensate it's former players for any alleged damages incurred, do you think all college and HS organizations, school districts, etc. have that kind of money? Eventually, there will be so much litigation that colleges and HS will just end their football programs because it will be too expensive to operate due to the risk.
Maybe that's what some people want? However, judging by the NFL's popularity I don't think that's the case. In any event, don't complain about the NFL pricing out the "avg. fan". Teams are going to recoup the money lost in litigation from somewhere.