There's more to it than the presidency. It's the GOP Congress that has been the problem.

You should check the stats. Pew says 85% of Republican voters were white. They did so-so among Latinos but bombed in the rest.

As for prospering, I suggest you check the data. The economy does better overall with a Democrat in the White House. The GOP is most famous for (1) kicking the props out from under the middle class, and (2) blowing giant holes in the budget, then leaving the wreckage for Democrats to clean up.