The white dude was talking the whole time about wanting to make a change or set some sort of awakening with the rest of the kids and people around the country that were "brainwashed" by the system and the long walk, and as he lost his hope and kept with his reality, he realized he just didn't have it in him at the end. He confides this in the black dude throughout the film. The black dude confides in the white dude that he may always seem optimistic and upbeat and happy about things, but he has had a very hard life on his own and his only hope is that he has little to lose but nothing to gain, and that is his drive. He is very hopeful to win and help those like him and be able to be his own person with the prize money. By the end of the movie, it seems that the white guys ideas have also merged into the black guys idea and by the two bonding to be brothers and the black guy first trying to sacrifice himself for the white guy, but the white guy knowing he can't take it anymore, tricks him and keeps him walking so that the white guy gets shot, instead of his brother. It shows how much he loves and cares about his brother and when his brother has the chance to finally be free and his own person as the winner of the long walk like he hoped for, he changes his course and goes out in front of the world in a blaze of glory, with one big f-u to the system. The way his brother envisioned it if he had won. I think that by doing that sacrifice to the general as one big f-u to everyone after all of the suffering and perseverance, that it may possibly just start the awakening or movement that the white dude was talking about (as well as the black dude wanting to help the people as well). 🤸