Ever heard of fake exit polls to lower Republican voter turnout on election day?
Gullibility. You trust the news too?
The only time pollsters miss is in off year elections because that's about 465 seats to poll, and nobody has the money to do multiple polls for that many seats. Foreign polling in ENG and Israel missed.
But in presidential elections, especially with this many polls, they are pretty accurate. You can tell an outlier like the one that one had Carson and Trump tied in IA. Subsequent polls showed that had Carson too high.
You can continue to dismiss polls, as I imagine you will, but you do so at your own peril. After twice doing that, I won't again.