how are the rights of 8 year olds protected that they can't go to a gunshop unattended and buy a gun? or a convicted felon? how can something be a "right" if it's revocable? how is the word "arms" defined? Why can't I purchase a grenade launcher (after all, if you really want to build a "militia" capable of defending against the British re-invading, you're going to need them)? The 2nd amendment in practice is subject to tremendous levels of regulation. The kinds of regulations most Americans want, e.g. simple waiting periods to allow background checks, are a tiny frill of a regulation compared to how heavily regulated "the right to bear arms" already is.
Because the second amendment isn't really taken seriously by anyone, not even the gun nuts. If it were taken seriously, it would become immediately obvious to everyone that it has become horribly dated by the advent of modern weapons technology and it needs to be changed. And then we could have an honest debate about where we ought to draw the line between weapons that people not in the military ought to be allowed to have, because everyone agrees the line needs to be drawn somewhere, even if it's just at WMDs. But no one seems to want to actually have that debate.
