It is, until it isn't.
> Also, anyone think that a US civilian militia has more than a snowball's chance in hell against any committed government-deployed force?
See: Middle East
That's always tricky because the most successful examples of a guerilla army winning like that are all a foreign army coming into a local rebelling population. They mostly work by just wearing down the invaders until the cost and time requirements wear heavy enough that the foreign army decides to just go home, that same dynamic doesn't map as well when it's the state fighting for it's own survival to me.
My biggest point is that all the often cited success stories of a guerilla army winning against any modern military are all on a home turf vs invading army (and the guerilla forces are often heavily backed by outside forces or backed up by an actual regular army like in Vietnam). There are completely different incentives there, on the extreme end of things losing means you might be killed
Also don't be so sure about Cuba if you're talking about the current situation, it's far from over and they're not exactly a peer comparison to make to a theoretical US insurgency.
Do you think the guns in civilian ownership are to be used for foreign wars? They are exactly for homeland invasion.
And who will back the US with arms? In the examples you gave it’s a richer country, or multiple, helping a poorer country. Who’s going to help the richest country in its death throes? What will be the benefit for all that aid should that nation fall? It’s better to pre-stage the weapons as that also serves to deter those that think the US is inadequately armed.
When presented with historical events supporting these claims your response is “cannot say with certainty”…
The interesting and terrifying part is, if I were China or Russia, I would be online trying to convince the US to disarm itself too.