They know that the black community currently can't organize an effective resistance, and too many of them are dependent on government to want to overthrow tyranny anyway. Whites are really the only threat to their power at this point. But please look closely enough to realize that this fight isn't Whites vs. Democrats. Most of the Republicans are obviously controlled opposition, getting their funding from the same community as the Dems, and only taking stances against the Dems on topics within the narrow Overton Window allowed. Mostly, despite verbal arguments and differing platforms, they both vote to move society in the same direction. In 30 years from now, when mainstream Republican politicians are taking the stances of Democrats from today, this will be more obvious to you. Or, you can take the shortcut to that wisdom and look at how liberal the current Repubs are by the standards of 30-40 years ago, and realize they conserved none of the rights and values we hired them to protect back then. American Federal politics is a shell game.