In present day America it is a relic.
It is not a relic; it is dormant. If you studied history you would know that it repeats itself. How long will the US government exist? Until the end of time? No. It will inevitably be gone someday.
We can not be sure of when or how it will end. When I was born, there were two superpowers in the world. Shortly thereafter, one of them collapsed under its own weight, yet without significant violence. That's one possible end facing the US. Another possible end is armed domestic conflict. It already came close to that once for this country- and historically, 150 years ago is not all that long a time.
Yet there are still those who fantasise about one day playing patriot and taking on the government in an armed uprising.
This statement is a non-sequitur. Anyone can make vague statements about groups of people who fantasize about things. There are people who fantasize about being king of the world, and people who fantasize about a peaceful, homogenous world where everyone believes the same things and gets along with each other. [By the way, I'd like to point out that John Lennon's "Imagine" is the most violent song ever written]
The historically accurate fact of the matter is that governments routinely engage in violence and sometimes their own populations retaliate against them for it. Nobody who seriously considers the ramifications of this holds any romanticism for it. Such claims are reminiscent of arguments over self defense wherein, pejoratively, opponents of self defense claim that advocates of self defense only seek it out as a pleasant, power-affirming experience. That is not the case. No stable person would ever
choose to be put in a position where they had to defend themselves, whether it was from rape, murder or government tyranny. However, some of the more rational minded among us recognize that rape and murder do as a matter of fact occur, and prefer to be prepared to defend against it. The same is true for the threat of tyranny, the rational men who constructed our Constitution recognized this, and attempted to reserve our right to defend ourselves against our own government. This is something which is occurring around the world at this very moment, and to deny that it could ever again happen here in the US is to willingly ignore the well documented cycles of history. Will it happen in our lifetimes? That much is not known. But to deny the very possibility is willful ignorance.