This is the problem. Too many people thought we HAD "fixed racism." Hey, we elected a black guy as president, right? Post-racism world.
Not.
The racists are still there.
It seems to have been exactly this. As much as People of color - particularly black people - were blaring the air raid sirens, far too many white people shrugged their shoulders and said "No, we're post-racial!" or even worse "Blacks are the real racists, Obama said his son would look like Trayvon!"
And when we pointed out that Dolt 45 was a clear white supremacist, and that he was recruiting supremacists and white nationalists who desired to kill as many nonwhite people as they could, well, we got "He wouldn't do that!", "Take him seriously, not literally", "He's just saying that to play to his audience", and the like.
By the way, what does that last one say about his audiences?
And now we have concentration camps, and white supremacists tried to terrorize an entire college town. Oops! Turns out Hillary had slightly underestimated the percentage of people who voted for him that were "deplorable".
Too bad it took all of this for people to say "Wait a minute, there are bigots still running around!" But (white) people seem to understand en masse now. And it's being reflected in polls - the white nationalists are louder, but the (white) folks that were asleep have also taken note.
(Course, many white people immediately, and correctly, identified Cheeto Benito as a white supremacist back when he was pushing birtherism back in 2011, so it's not like it's a lack of melanin that causes people to miss all this. If you didn't pick up on it right then and there, you may want to consider why you missed such an obvious sign.)