The further fallacy is that if it came to a fight against our own military, half or more wouldn't defect to the "rebel" side, taking their advanced training, arms and equipment with them. If the government somehow got the full and enthusiastic cooperation of the US Military, or came up with its own brownshirt corps of private troops equipped and trained to the same standard, resistance would, for the most part, be futile.

There'd still be some fighters even so, and it'd go on for years or decades - whether or not the citizenry were ever armed, until everyone who'd ever heard of liberty was dead or working for the oppressors.