Keeping in mind that our Presidents have been GWB and Obama for 14 years and that's a lot of built-up dissatisfaction. There's also dissatisfaction from a lot of older voters who remember the potential and expectations for the US in the '50s and '60s and are disgusted with how things are now.
The article mentions the Federal Reserve. Rand Paul hasn't even brought that issue up yet. That can bring in a lot more fed-up voters, if the mainstream candidates continue continue to mostly support the status quo.
Is there enough fear or dissatisfaction or disgust with the way DC is messing up the US to propel Rand Paul's candidacy? Who knows? But yet again with the NSA vote, Rand Paul got out there, ruffled feathers, and made mostly uninvolved US voters take notice.
People here love to bash Rand Paul, but lately he's been on the right side of several issues, unlike many of the so-called "Constitutional Conservatives" running for office.