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inherent variance in elections is extremely minimal. The odds in elections are more representative of confidence in your sampling than a product of randomness. What I mean here is that if you polled each and every person who would vote, the result of that would tell you who is going to win with a practically negligible level of variance. By contrast, even the best model for something like a sports game is going to be probabilistic.
Imagine a thought experiment. We're able to do something 100 times, each on a consecutive day, but without any knowledge of what happened on previous days affecting the future, and without any future information or events affecting original 'intent'. If you played a sports game 100 times you'd generally get a wide distribution of results. But if you ran the election 100 times, you're generally going to get the same result.
The point here is that Trump winning did not indicate a 'low probability' event. It indicated a dramatic failing in sampling. Why was this? The 'art' in sampling is not only obtaining a representative sample, but actually determining what a representative sample even is. And the radicalization of our society is making this more and more difficult. The media was running bits literally comparing Trump to Hitler, individuals have been assaulted, robbed, and denied service simply because somebody became aware they supported Trump, and even business leaders have been harassed to no end for doing things that could be seen as supportive of Trump. Like you mention even pollsters that didn't cheerlead a completely crushing Clinton victory "got shit" -- that's all just completely absurd! This creates a chilling effect where individuals are going to be less inclined to respond, and/or respond honestly, when queried about their views. Then pollsters are left to rely on incorrect information which hampers not only sampling but even in the determination of a representative sample.
And the point of all of this now is that presumably most pollsters have tried to change their ways. But this will be the first election where that will be put to the test. So unbiased aggregation is more informative than ever. 538's "adjustments" were based on past polls before we had such social extremism, and by relying on them alone for their first real test - well, that's a huge leap of faith.