The problem is this, Under President Donald J Trump the black unemployment has NEVER been lower. Game/Set/Match.
While that is accurate, you are making the erroneous assumption that people will usually vote in their own best interests. Blacks have demonstrated for decades that is not the case. IMO the same can be said of US Jews. The Democrat party is a hotbed of antisemitism and that seems to be a non issue for US Jews.
Yes, I am making generalizations, but it's those that matter. Outlying exceptions are just that.
I hope I am wrong next November, but I'm not betting the bank on it.