None of your examples prove that armed American civilians could defeat their own military.
* the Iraqi insurgency is actually a full scale civil war, with Russia supporting the rebels
* Afghanistan: the country has been in a state of civil war for years, with different factions supported by various foreign powers
* Syria: the rebels are supported by Western powers, and they're still losing
* Yemen: the rebels are supported by Iran, Hezbollah and North Korea, and they're still losing
* Vietnam War: North Vietnam had its own army, and was supported by China, North Korea, Cuba, the Soviet Union, and the Khmer Rouge