Black voters are more rational actors than white voters. Black Republicans are generally upper class. It makes sense.
It's these poor whites complaining about the moochers not paying income tax that make no sense.
Actually it makes plenty of sense. Working class people compete with other working class people in the free-market capitalist economy. It figures that many of them-even poor ones- will internalize the "pursue your own economic self-interest" ideology that we all hear (and internalize to some extent). That self-interest is individual, and comes at the expense of others of the same status; additionally, a lot of people in this stratified system feel threatened by the people
lower than them in status, even (or perhaps, especially) if they themselves aren't doing well economically. Hence, the complaining about "the moochers not paying income tax" or "welfare queens" (although to be fair, that kind of thing cuts across class lines...)
It's different for black Americans obviously, because traditionally, they've been excluded
as a group from the society at large, to say nothing of how limited social mobility has been for black people in America. Working-class whites (particularly white native-born men) have always had better prospects than non-white poors, relatively speaking.