The whole point is for the citizens to be able to form a militia in order to defend themselves from their own government.
That might have been the case in 1791, when the strenght of an armed force was roughly proportional to the number of men with guns it had.
Today, if you would pit every civilian gun-owner in the US, with all their weapons, against the forces of a single aircraft carrier (one thenth of the aircraft carriers that the US government controls), the civilians would lose. Hellfire missiles beat automatic rifles every time.
If you want the second amendment to imply that the people can defeat the government by force, then you either have to massively reduce of the government-controlled armed forces, or allow civilians to own cruise missiles.