Last I checked, Hillary won the popular vote by a mere 200,000. That's about 0.3% of the total votes cast, and about 0.15% of the voting-eligible population. That's barely even a rounding error. (Also enough to throw Pennsylvania in the other direction. If that had happened, we would still be counting votes right now.)
That is very sobering. We can confidently say that for every four people in the country, one cared enough to vote for Trump, one cared enough to vote for HRC, and the other two couldn't be arsed to do either.
On the other hand, why would we expect anything else? This is how it's turned out - with only a slightly larger rounding error - for the past four elections, back to 1996 and 1992, when Ross Perot threw a gigantic wrench into the Republican works both times.
So really, this outcome is just another instance of a regular pattern. The real question is not "why didn't we see this coming", ... it's "why did we ever expect anything else?"
A "prestige" vote is too self-centered of a theory. It carries the tacit assumption that the media we (democrats, in my social circle) have been consuming is the only collective media feed in town. We didn't hear about these people through our channels, therefore they were silent? I think it's more likely that the channels have become more and more balkanized, inviting us to accept a more and more distorted view of what "the country" thinks.
"But how can that be?" you ask. "Everyone hated Trump, everywhere I looked! Especially the media!"
How often these days do you - how often does anyone - come across a piece of news because of the actions of a journalist, or the actions of a journalism-focused apparatus like the county newspaper that my father would spread across the table a few times a week? ... And how often do we come across it because it was handed to us in a Facebook feed, or a comment thread, or a tweet, or a text message, or an email, or a search engine that has been studiously trained to show us something it thinks we'll click on? (These channels are the very definition of selection bias.)
How often did we participate in this same distortion, by only passing along the articles we enjoyed reading, the memes we laughed at, the polls that encouraged us - or called us to action by making us angry at a monster?
How much of this election was given to us for the sake of ad impressions in web browsers? Including those following it internationally? It's not so hard to imagine that a full quarter of the population can spend most of their 'news-reading' time eagerly devouring scandalous editorial takedowns of a candidate they loathe, considering themselves well-informed for the effort, and then getting a rude surprise when the votes come rolling in... And no one had to be silent, or even feel particularly embarrassed, for it to happen.
We convinced ourselves the outcome was inevitable.
Did Kellyanne Conway single-handedly engineer the election, even though she managed Trum's campaign for only three months, and spent all of that time applying spin and damage control for the sake of Republican voters tempted to jump ship? Did Gary Johnson and Jill Stein spoil the election with their third-party antics, even though the Libertarian ticket appealed to angry Democrats and Republicans alike? Did FBI director James Comey derail the whole election with his letter, even though a much more damning scandal - the Access Hollywood recording - didn't take down Trump, despite being prominently discussed at the debates? Or would a better equivalent be the HRC email scandal and the Benghazi hearings, both of which boiled away for over a year, but accumulated an epic backlash?
We could speculate about how many minds these things changed. But we might also want to speculate on how many minds were willing to change in the first place, because in the end it all came down to a difference of less than a rounding error, and as usual, half the population didn't even care enough to vote at all. Meanwhile, we arranged our filter bubbles to make each of us into a champion, fighting on the righteous side against pure evil, and even amongst those of us who was ethical enough to try and only pass along things that were true (rather than the beneficial lies), we nevertheless only passed along the parts of the truth that bolstered our cause, and conveniently ignored the rest.
Face a real fact: Half of all voters voted for the other candidate, because they were convinced it was the better choice.
Call them stupid and they will call you corrupt, or vice-versa, and we all go around this carousel for another four years. Or just accept that party affiliation - and your family and social circle and workplace and church - forms an information bubble around you, and the best you can do is navigate it with some awareness, and hopefully some f*&% class as well. Remember: It's very, very easy for the people you vilify to tune you out. It's so easy you won't even notice them doing it. And if you're like most people, you won't even care. People want to feel like they are right - perhaps even more than they want to actually be right.
If we're surprised, it's ultimately our own fault. Time to open the filters back out again and see all the people we've painted as monsters and find some way to understand each other.