Trump supporter might be worried about the polls, even if they are closing a bit of late. Then again, they might not be worried, seeing the polls as misleading. Many of us did that erroneously in 2012, and Trump supporters should be warned by that head-in-the-sand-aided-by-confirmation-bias world view. One of the things I worry about is the notion of attendance. Trump supporters and indeed Trump himself are conflating two different notions. They argue that the polls are wrong and Trump is winning and the proof is that he's getting thousands of attendees at his rallies and Hillary Clinton is getting hundreds or even dozens. There are a couple of problems with that idea.
Firstly, and no less importantly, just like Clinton is avoiding press conferences and is being handled with exacting standards, I suspect her approach in facing Trump is that less is more. She's avoiding big crowds and longer appearances in the hopes of avoiding a slip-up (which she is clearly prone to make). The smaller crowds might be by design.
Secondly, when looking at the size of a crowd, what we really are trying to guage is the depth of support, not the breadth of support. How many supporters a candidate have is the bailiwick of pollsters. How engaged those supporters are, is measured by turnout to a rally. Trump's supporters are truly energized, but it does not mean there are more of them than Hillary supporters.
As an adjunct to that latter point, engagement still needs to translate to action to be useful. Are Trump supporters organizing themselves and going door-to-door to promote Trump? There's no evidence of that, at least in the news.
All that not to say that Trump supporters are mixing up rally attendance with the truer picture provided by the polls. Polls can be wildly erroneous if constructed incorrectly. And Obama had massive rallies too in 2008, so it's not meaningless. But conflating enthusiasm with numbers (support ten feed wide but a mile deep) is a mistake Trump supporters and more importantly Donald Trump and his team are advised not to make.