Tyrian, as usual, you have some insightful observations.
I think the "tyranny defense" argument is about 80% empty rationalization in the minds of many people in modern times. Our government indeed possesses weapons so
far beyond civilian capability it's almost irrelevant for the individual. The interesting part is how that ties into our 2nd amendment. To me, it seems pretty clear the purpose is the states have a right to protect themselves from federal power via their own militia. The reason that point is so important, and confusing to many people, is because America was built to run from the bottom up, not the top down as countries have traditionally been run elsewhere in the world. For example, the states have the power to do away with the Federal government if they want to, where as the Feds have no such power over the states. This penetrates American culture down to the individual level. There's a long standing tradition to challenge the notion of "taking one for the team". Our culture has a history of " freedom over safety". Controversy arises when the crazies have access to weapons used to carry out mass-murder. If you don't build a proverbial dam somewhere, you get into a situation where people obtain increasingly powerful weapons that far exceed personal self-defense and only purpose is offensive carnage. This is where many Americans, even pro-self-defense ones like myself, are readily willing to talk safety and sanity.
This transitions well into the "safety argument". I don't think, and will have a hard time being convinced, that anyone should have an equalizing line of defense taken from them in the event of, say, a home invasion, and be forced to wait with their fingers crossed for the authorized public defenders to arrive. The common misconception that people think about Americans is that this means we don't feel safe here. That's not true. We do. America is getting statistically safer as a whole all the time. I have several foreign friends I hang out with often and they say they're surprised at how safe it is actually. They say they want to stay here because you can walk around in big cities at night and not have to worry about being mugged (FWIW, they're from Brazil and India). I understand your point about criminals having access to guns, which here, they still will, same as they do with drugs, prostitution, anything on the black market. When I was growing up, marijuana was illegal in all states, but you could buy it from a kid at almost any high school... and these are kids. There are ways to combat criminals preemptively here. Perhaps further restrict the classifications of guns that can be bought, do away with all unregistered sales, increase the penalty for having an unregistered gun, increase the penalty for use of a firearm to commit a crime, etc. Plenty of folks have ideas that still allow for personal protection while raising the stakes for criminal activity.
I'll end on the "trust issue". I don't think Americans have a hard time trusting each other. Wherever you go, the vast, vast majority of people are completely unarmed. The idea that we're all walking around flashing heat, looking at everyone surrounding us wondering "are they gonna try to hurt me?" is laughably false. People are people, the world around. 99.99% of us would rather not deal with issues of lethal self-defense constantly. I personally find it depressing. In reality land, we all just want to do our jobs, hang out with friends and family, go see that new comedy movie everyone is talking about, etc., and not worry about it. Again, I think self-defense is like wearing your riding gear. Ideally, it'll never, ever be necessary, but when it is, it could safe your life. I'm no gun-nut. more a moderate like some of the others who have chimed in so far. Safety and potential-for-mass-killing are 2 totally different things, and I think most of us understand that.
(I still wanna know how Canada manages to do so well with it. I've always admired that about them.)