It just happens. Did anyone plan the American Revolution. Would it have happened if British troops had not marched toward Concord, Massachusetts to confiscate arms from the Massachusetts Militia warehouse?
We don't know how the military would react if there were riots or if there was a Waco type incident where thousands of armed Patriots showed up spontaneously to defend against gun confiscation.
There are many people who are today quietly waiting for the trigger event. The action of one man or a few men might embolden them to act. Guerrilla warfare does not mean big armies of rebels meeting government troops on the battlefield; it involves assassinations, bombings, sabotage, small scale raids, and the like, and a significant part of it is neighbor against neighbor violence. Look at Iraq or the IRA during the Irish rebellion.
"Bend over and grab your ankles" should be etched in stone at the entrance to every government building and every government office.