Pedantic arguments aside, the riot was probably organized by some professionals with an agenda. That much seems certain at this point. And their purpose was to delay the certification of election results. In other words they were subverting democracy - an insurrection. They weren't necessarily planning to take over the government and fight off the US Army in a literal way, but they were somewhat violently (It obviously could've been worse, but organizers knew that extreme violence would be met by extreme retaliation) trying to overturn a democratic process. So why did they fail? Perhaps they expected more conviction from the crowds that actually breached the building. Those guys got the hell out of there when the national guard showed up.