The 2d Admendment is still valid today because we have a legal system that continues to put violent criminals back on the streets and doesn't put them away for life and throw away the key.There's a couple reasons that the amendment isn't all that pragmatic any longer.
1. To protect yourself from the gov't, you'd need a stockpile of nuclear weapons greater than the rest of the world combined. When this amendment was written, a bullet didn't even exist.
2. If you really tried to protect yourself today, it would be considered terrorism
3. The amendment protects the rights of "the people" to keep and bear arms without being infringed. However, in practice, certain subsets of the people are prevented from buying guns - mentally ill, criminals, children for example. We've essentially been enforcing this amendment randomly. So why not just say everyone falls into a subset of people considered "idiots" and selectively decide they can't have guns. This is supposed to protect all the people, but it doesn't. We decide some people can have guns and others cant.
4. The amendment is about a militia being necessary for the security of the free State. This is about state's rights vs the federal gov't. Again, my state isn't stockpiling nuclear weapons. Is yours? Do the States still need to protect themselves from the federal gov't by their own militias? It's not pragmatic and won't ever happen.
At the end of the day times change. Technology changes. People change. Things that had meaning for a particular people in a particular time period don't necessarily have meaning for people in a different time period. I think we should try and read the amendments through the lens of the people of the time period in which they were written and extract their meaning through those lenses. And if things are applicable today, great. If not, they're not.
I don't see how the 2nd Amendment makes much sense for us today really. It's nothing that the NRA and gun fans try to tell us it is. I doubt most people have read the Bill of Rights. Here's #2. This makes little sense to me in the context of current society.
"A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed."
And at the end of the day, even Thomas Jefferson said:
"Strict observance of the written law is doubtless one of the high duties of a good citizen, but it is not the highest. The laws of necessity, of self-preservation, of saving our country when in danger, are of higher obligation."
So I would think that TJ might feel that gun ownership in today's society may not make sense or be the intention of the 2nd amendment. Again, these guys hadn't even seen bullets yet, let alone the stockpiles of weapons of the US military. It's actually quite laughable to consider the states could have their own militias to defend against the US military.
It's quite possible that TJ and others thought very similar to Chadman. And the intent was never what the 2nd amendment has been turned into by the marketing of the NRA. Guns, weapons, military, regulation are huge business in the US. This amendment doesnt protect the people, it protects the vested interests of people that make money selling guns. Fear is one of the best motivators for people to spend money. In a way, this fear has been used to control us all and enslave us to the system. It's become impossible to protect ourselves from the system which was the original point. But we have our guns. And we feel like we're in control. But nothing could be further from the truth. How can a man in fear ever truly live free? Tyranny owns us.