You have to look at the demographics of this...
Yes, you have 1 group (and had that group been alone, Clinton would be President) that group is the White, Male/Female rural, suburban vote that has never voted before (hence why they were not counted in all of these polls), they came out of nowhere in the states that Trump needed, in just the amount of votes to push the electoral count his way). *shrugs shoulder* who knew?
But, the 3 demographics that were forgotten by the CLINTON CAMPAIGN, and one of those WAS NOT FORGOTTEN by the Trump campaign at just the right time? is what won this election for Trump.
Group #1: Bernie supporters, the Clinton campaign never gave them a second look, they thought they would follow the party line. THESE WERE YOUNG, COLLEGE EDUCATED 20 AND 30 SOMETHINGS, they don't follow, they walk beside, and the Clinton Campaign left them behind. They did not vote....
Group #2: Those that came out in huge amounts for the Obama Coalition, the black, urban voters of the "Blue Wall States"...the Clinton campaign paid them little attention. They did not vote....
Group #3: White, blue collar union workers of the rust belt, the Clinton Campaign paid them little attention, and Trump at the right moment DID, stayed on point, and got just enough of that normally SOLID DEMOCRAT VOTE to turn his way....
You take those that did not vote at all (but voted for Obama), and those that normally vote Democrat (voted for Obama) but went for Trump this go around because of jobs lost and Clinton did not seem to care.... and add those to this crazy new voter from rural, white Suburban America, and you have a narrow win by someone like Trump.