It will take about a week to ten days after the democratic covention to sort out what is covention bounce and what is a long them trend. By Aug 15th the polls should be, if history is any guide (FWTW up this year), reasonably predictive.
I always expected the the election to be reasonably close; politics for most voters is less a rational selection of choices than its tribal, a form of identity. It was inevitable that most republicans would rally to Trump as democrats will rally to HRC. Given how close most elections have been for a long time anybody expecting a blowout was kidding themselves.
Now you can argue that nobody in their right mind would vote for the most obviously unqualified, by resume and temperament, candidate president perhaps in the history of the republic - and I'd agree with you. But most Americans, like most people everywhere, aren't that bright and really aren't that thoughtful about politics.
People do stupid sh*t all the time; they buy Pontiac Aztecs, watch reality TV, and eat at chilies. It would be nice to think that electing a president would be a bit more serious but in the end it's just another consumer choice and people make lousy choices all the time. For some companies lousy choices are a business model.