I don't think I've actually ever really understood this aspect of American paranoia.
I think the claim is simply that it can potentially change the outcome.
And before anyone disagrees, how many soldiers died in Iraq & Afghanistan at the hands of insurgencies?
Philadelphia bombed a city block to flush out an entrenched armed group in the '80s, and life went on (for everyone who didn't have their home burned down). Don't underestimate the American capacity to believe something was done because it was necessary. It's the only country to have ever deployed nuclear weapons. Twice.
What are the 2 most-armed civil societies in the world? US and SUI
Then you have the other end of the spectrum: is regulation of private gun ownership predict government turning on its citizens? No.
Is regulation of private gun ownership a prerequisite for authoritarian govts to turn on citizens? Yes
If anything, it is mistrust.
The whole point of the right to bear arms is that they're meant to be used against the government when they overstep their bounds. But what happens when the people who bear said arms agrees with how the government is breaking the law?