I'm not too familiar with him, but if I understand what I've read correctly, I think he holds such views because, as another poster said, it's nihilism.
He's probably literally had to deal face-to-face with the purest form of white supremacy which probably changed his views. Having to adjust what he feels is the trivial aspects of his belief to stay true to the core. Not everyone is gonna be strong enough to never change. Of course he's not gonna be the same optimistic individual he might've been early in his career to what he is now decades on. Black people falling for literally the same tricks has probably contributed to his apathy as well.
It's kind of a 'Die a hero or live long enough to become the villain' scenario. (Is it bad I kinda agree with a lot of his points?)
Edit: also, from an outside looking in perspective, why should y'all leave and not fight for what you contributed to creating? Spend literally centuries building arguably the greatest nation on Earth (far as opportunity, resources and quality of life standard) just to be punked out by injustice? I think y'all should keep up the fight. And considering white people dying out, I think the biggest concern black people in America have is c00ns and self sabotage. I think progress would be ten-fold if you did what the Haitians did to be honest. c00ns die first