Oh, it absolutely is one of the rationales behind the USA's second amendment. The problem is that rationale just isn't relevant today, and believing in it is the height of naivete. Even if you got every civilian gun owner in the US to secretly band together to overthrow the US government[0], the US military would pound them flat[1] before you could say "reload".

[0] Good luck with even that much.

[1] Without even touching the US's nuclear arsenal, though they might opt to level a city in clear, full rebellion as a deterrent. They'd still do fine without nukes, though, as devastating to the US population and infrastructure as it would be.