"Any number of blacks" are "terrified of losing their white privilege?" I'm having a hard time finding the sense in that statement.

What are "the Black Riders"? Are they like Red Rider, the cowboy hero? Are the like Easy Rider, the biker dude? Are they like night riders,  blowing up churches and synagogues and lynching people? Provide us with a definition please, and a link to your source of information. You want everyone to know the truth, right?