There's some degree of weird essential tribal affiliation in racism, but a lot of white people in America do believe that white people are superior (whatever that means) to black people and that the system is rigged in favor the latter. The two work together. Black people fail DESPITE getting all the good breaks, what did I tell you? Those people can't even succeed when their obamaphones are just handed to them!
I don't know if there's any utility in calling this basic racism "white supremacism" but that's what it is.