As has already been pointed out on this thread, using nationwide polling data that only predicts the nationwide popular vote is useless as the outcome of a Presidential election depends on the results of the Electoral College selection. But, the media, the politicians, and most Democrat voters were convinced by this wrong headed approach that Hillary would win. They were wrong.
The blue wave predictions have been based on these same sort of polls. As local and state wide polls are starting to show up, these raw results are being influenced by the earlier blue wave polls. This is circular logic, but it makes the media orgasmic. The coup d’état crowd must be really excited.
Expecting Hillary’s performance with black voters to equal Obama’s didn’t help either.