What you’re missing is that the average salary of the kneeling player is far above that of the average fan. Kaepernick had a $114 million contract with a multimillion signing bonus. Pro athletes in America are a privileged class. They were extolled by booster clubs in high school and given easy pass classes, girls, clothes, cars, and fancy gifts in college. When a local cop catches them speeding, they get off with a verbal warning. The rules that apply to everyone else don’t necessarily apply to the star athlete. When an average fan sees the kneeling pro athlete, they see an individual trying to get special treatment on the job. Much of the deep resentment is the feeling this is a statement of an entitled millionaire saying he can get away with behavior that would get the typical worker fired on the spot.
The angry fan sees what is instantly interpreted as disrespectful to the symbol of national unity and doesn’t care what it’s supposed to mean. This mode of protest deeply discredits whatever the ostensible cause supposedly behind it. By way of contrast, Dr. Martin Luther King marched on the Selma bridge with many American flags flying.
Ultimately, it’s hard to think of a worse way to protest oppression than to have a bunch of coddled millionaires insult the flag.