If there is so much racism in America, why do white people want to be not white? Why are they giving up their supposed “privilege”?

I heard an interview with Mike Shellenberger the other day in which he pointed out that if he declared himself to be a woman, his lefty friends would encourage him, but if he claimed to be black, they’d denigrate him. Yet (as he pointed out) he has a much more biologically in common with a black man than with any woman.