Kaepernick certainly is fighting for his country. Is that what you mean? He's currently unemployable, being willing to sacrifice his livelihood for his beliefs. Isn't that sort of heroic? 

People join the military for all sorts of reasons. Black folks joined during the Civil War to fight slavery. Frederick Douglass saw military service, incorrectly it turned out, as a claim for full citizenship for black men. For many poor people, the military is a way out of the impossible circumstances in which they were born and grew up. 

Many joined after 9/11 thinking that Islamic extremism was best countered by full military mobilization of the populace, as during WWII, when millions signed up because Japanese imperialism and Nazism threatened America's existence.

It needs to said, though, that many African American veterans have routinely found that their military service, in ANY period, has NOT been a path to full citizenship.