There are a lot of good points being made here. I did want to add perhaps another point to consider. Athletes, musical artists, actors and really anyone in the public eye are judged by a different set of rules than the general public. In the case of sports, it's only when an athlete misbehaves that we hear of them. There is a always a rush to judgment without knowing the facts.
These people are in fact a small minority. There are a great number of athletes, musical artists and the like who give of their time and money freely and without any fanfare and do so in an anonymous fashion. It's never reported as reporters spend more time trying to become the news rather than report it. The good deeds by these athletes / artists are rarely reported as quite honestly, tabloid news relies on the ratings and revenue of reporting distorted facts and bad news about people.
I personally know a gentleman who played football in my hometown for a rival football team. This man went to college and played football professionally in the NFL. He earned various degrees with hard work while playing football and even after he retired. After his playing days were over, he accepted a position with a junior college and took it upon himself to initiate what can be best be described as an " outreach " program. The goal of the program is to help those individuals trapped by crime in the inner cities into being able to make positive changes in their life with the ultimate goal of going to and graduating from college. He also works with a number of past and present pro football players from the local team with the same goal. As he once told me, " These kids are really the only thing that matters." It goes without saying that I have a great admiration for him even though his football team used to pound mine every year.
He has been offered better paying and more visible positions with better known 4 year colleges but has turned them down. He told me he wouldn't be able to do what he is doing now and as he said, " these kids need me." This is just another example of people who toil in anonymity. News like this is never reported because it's not considered " newsworthy. "
In the case of the current pro football players, I truly believe that they wanted to use their high visibility to do some good and call attention to a disparity in law enforcement. The disparity may be real or perceived but certainly, video footage has captured citizens being outright executed by over zealous law enforcement. Using the same logic as above, these officers are I'm sure in the minority and also make decent law enforcement officers look bad. Although the football players efforts backfired, they can be commended for coming together to make positive and concrete efforts to bring about some much needed changes.
As for the National Anthem, I stand and salute no matter if I am at the actual sporting event or watching on TV. I'm sure others do the same for their respective National Anthems in their own countries.