Clrnc
Or a swing voter could decide to stay home and not vote since 'eh, X or Y candidate is going to win anyway, why bother'.
Polls are bullshit. It doesnt matter if Thiel is taking the most trustworthy polls, all polls are bullshit to begin with. People will say or tell whatever they want, but when they're alone in the booth, they will vote for whoever they want to vote for. And early polling is always skewed to one candidate or another based on who is sponsoring it. Believe me, i used to work for a company that did the Harris Polls.. (no pun intended).