The point is that the Constitution never granted the government the power to write law denying the citizen his individual rights. The Second Amendment was written to protect the citizens inherent right to individual gun ownership from government interference. Without the Second Amendment the government still would not have the Constitutional power to write law interfering with the citizens individual right to gun ownership. If the First Amendment was not there to protect the citizens inherent right to free speech and worship the government still would not have been granted the power to write law that interfered with the citizens right to free speech and worship.
A right does not require a reason to be a right. The position that if a valid reason cannot be proffered then the right does not exist is incorrect.
The Second Amendment could have been written A Sun rising in the east being necessary to the security of a free State, the right of the people to keep and bear arms shall not be infringed. The individual right to bear arms would still exist. A citizen may exercise his right to gun ownership for the purpose of using the gun for self defense or he may use it for a paperweight if he wishes.
I am fond of this observation of Thomas Jefferson. Thomas Jefferson, by no means an imprecise thinker, was well aware of this consideration. In commenting upon how the Constitution should properly be read, he said: "On every question of construction let us carry ourselves back to the time when the Constitution was adopted, recollect the spirit manifested in the debates, and instead of trying what meaning can be squeezed out of the text, or invented against it, conform to the probable one which was passed.
Here, Here!
It is annoying to no end that otherwise intelligent people just can't (or won't) understand that the Bill of Rights does not make law, but is a statement of that, which the government is denied tampering with because these rights existed BEFORE government.