To me, there was a confluence of things.
White America has really severely disliked Hillary for decades. I don't know whether it was the "not baking cookies" comment or taking back Bill after the affair but the fact that White women abandoned her, says a lot.
Many bore a grudge against Obama, never accepted him and seek to stamp out his legacy. Don't let the popularity/approval ratings fool you. People will say one thing in surveys and do another at the ballot box. There is a contingent that is especially bitter that Obama won a second term and sought ways to obliterate any chance of a defacto 'Third Obama term' in a Hillary Clinton administration.
Also, some Black millenials (and some Whites) complained that Obama let them down, didn't do enough-- forgetting completely the obstructions he had to face. For me, the one mistake Obama made (if you can call it that) was to believe that Republicans would be reasonable and respect him as Commander-in-Chief and work with him to pass actual legislation. Nope. Well, those who think that Obama fell short, are really going to learn that it can get much worse.
The real "rigged system" was the voter suppression that went on in many pockets that had minority populations. For every voter that went to the ACLU or NAACP to lodge a complaint and asserted their rights. Many more were dispirited and gave up. The repeal of the Voting Rights Act, meant many GOP headed states were free to close or, move many voting stations out of urban areas with a more diverse/minority population in favor of suburan/exurban less diverse/Whiter communities.
It's downright dispiriting that the media is underplaying or not reporting the role of voter suppression, voter intimidation in all of this.
That is going to be a rift for some time to come. Also immigrants. I know some recently naturalized U.S. citizens who voted in their first election yesterday and they are dispirited, depressed. I haven't the words to tell them.
Charles Blow is on Twitter right now tweeting that he is struggling for words. In response to someone to tweeted @him to talk about white supremacy and anti-blackness, he said:
" I've written about this so much that I'm not sure that I have a new way to discuss it. It exists. It's a problem. America doesn't care... "
Many people, including me, feel a breach of trust. I feel more self-conscious of the gulf between what people say and what they do. What people say to my face versus what they are saying when I'm not in the room. What 'they' truly think about me despite their words and rhetoric.