Has anyone ever told these wizards that they make up about 10% of the population?
And a percentage of that percentage is locked up in jail/prison and not available for rioting in the streets. They could try to riot in prison, I suppose.
I dunno if St. Louis education is that dismal, or if the kids in St. Louis are as likely to stay close to home as some places in New York (some of these kids had never been more than five miles from home!), but IMHO it's certainly possible that a fair percentage honestly don't realize there are so many more white people. And they definitely don't realize there are great swaths of the US full of white people who rarely, if ever, interact with someone black, simply because everyone is white for miles and miles.
One of my dad's cousins married a black African, who now lives in rural Minnesota; he is literally the only black person a lot of his neighbors have ever interacted with outside of vacations or visits to the Twin Cities. The irony is that that he is probably dealing with less culture shock than some black guy from an American inner city would!