Football players do not have a right to protest on the field, in their uniform and as representatives of their employer.  If the employer decides to let them they can.  As this happened, the NFL actually has rules that forbid the activities these players participated in for all the obvious reasons.  The NFL decided to ignore their own rules specifically to disrespect the flag, their customers, and spite the President.  If fans who come together from all walks of life regularly to unite despite all differences for the love of the game, witness the utter disregard for the fans, the flag and their President, then fans have a right to say "stop or I'll leave". I may not bye a cheese burger from a fast food restaurant when I don't like their product in the same way.  I can't tell my customers that my personal beliefs are more important than their or that my personal beliefs are relevant at all to my customer's.  If I do that, I would expect to be fired per the rules of my employer.