Pretty much most of the polls have been wrong since 2012. Mitt Romney was projected to win late in the game yet he easily lost to Obama. Same in 2016, which gave Clinton a 91 percent edge over Trump.
The fact is that pollsters target people with landlines who still pick up their phones even when caller IDs list them as unidentified. That's mostly the older demographic, not the younger sorts who only use a cellphone and wouldn't answer numbers they don't recognize. And don't even get me started on internet polls which are easily manipulated and allows people to vote more than once if they have different IPs (which are so easy to manipulate for anyone online that has half a brain anyway).
Translation: polls are fucking bullshit.