Not sure the polls were all that wrong. As Nate Silver pointed out throughout the campaign, the problem with polling for the presidential election is you have to aggregate polls for fifty different jurisdictions, and state-level polling is subject to a lot of problems. If you look at the national polling, it was well-within the margin of error (HRC will win by at least 1%). He also gave Trump a 30% chance of winning in his last poll, which was hardly an insubstantial probability. And, then, in fact, Trump actually won by virtue of carrying three states by a margin of less than 1%.