alt Hacker NewsFiveThirtyEight gave Trump a 30% chance. Their reporting did make clear that with margin was within the range of a normal polling error. And sometimes you get more than a normal polling error.
It doesn't help that the US has a terrible election system that often leads to small margins in some states being decisive.
> FiveThirtyEight gave Trump a 30% chance.
I know I'm being super conspiratorial here but why wouldn't all forecasters predict just between 30% - 70%? That way if they're "right" they can take the credit for it and if they're wrong they can say "well, we weren't that wrong". That's probably what I'd do anyway...