Halon- our Constitution also originally declared that black people counted as 3/5 of a white person, that it was legal for humans to own other humans, that women were unable to vote, and declared for a period of 25 years that alcohol was illegal. The beauty of the constitution is that it was made so that it could be changed. The writers were not arrogant enough to believe that they were correct about every issue.
We've already "dismantled" more than a decent portion of this document through amendments- 27 of them to be exact including the 10 included in the Bill of Rights. (Which further shows that gun ownership was not originally part of the document but had to be amended in). Pretty sure the US has been going pretty strong since then.
In fact, your argument about devolving in to chaos is the exact same one that anti-slavery activists used when opposing the abolishment of slavery, and the same one used when they gave women the right to vote (although they may be right about that one
). The beauty of this country is that we can change over time.
Like I've stated before, I don't support repealing the 2nd amendment. I have no problem with everyday citizens owning guns. I do have a problem with people claiming that additional restrictions around citizen gun ownership (licensing, training, mandatory minimums) will cause the fall of our country and the invasion of our enemies. US soil has been directly attacked a handful of times in our history- War of 1812, technically the Civil War if you want to consider the confederacy as an "invasion", Pearl Harbor (although Hawaii was not a state at the time), and 9/11. None of those had anything to do with whether or not everyday, ordinary citizens held guns in their house.