There are three primary reasons the Second Amendment was ever created:
1) The authors claimed that, at the time it was written, the national military force was not mobile enough to provide full protection to the country. We were a very young country that just finished a revolution and there was legitimate fear that numerous European forces would attempt to invade or grab land around us. Thus, the authors proposed the idea of
state run/regulated militias, which would act in the event of an invasion until the federally supported military could make their way to the location.
2) People lived on the fringes of the land we had claimed as part of the US. There were constant battles between Native Americans and "colonists"/now US citizens. The national military force couldn't be anywhere and everywhere at the same time, so it was necessary for the people living in those regions to have firearms and regulated militias in order to protect their lives, land, and the claims the US had on the land.
3) The Anti-Federalists, who were responsible for pushing the Bill of Rights into the Constitution, were opposed to a strong, central government as they feared any government not heavily regulated by the citizens would inevitably gain too much power and become corrupt. The Second Amendment was, in some form or fashion (probably an idealistic one), supposed to serve as protection from a corrupt government.
Now clearly, in the last 200 and some years the scenery has changed...um a hell of a lot. The first two reasons listed aren't all that valid these days, I think that's something everyone can agree on. The third is very idealistic and frankly extremely naive. If we assume the national government became so corrupt that it started some "Reign of Terror tactics" in the US, I think we can also assume they would make use of the US military. A bunch of disorganized citizens in various states across the huge expanse that is the US don't stand a chance against arguably the most powerful, mobile military in the world...I don't really care how many AR-15s you have, not a chance.
But regardless, I support a person's right to own a firearm. I don't own one personally as I don't feel it's necessary, but there are arguments for both sides. I think it's fair to say there should be stronger regulations and they should be more difficult to obtain (and much more enforcement on the Black Market is very necessary).
Oh good, I get to get into politics. Forget the second amendment. If the Government has its' way, we won't have that amendment for to long.
Don't be ridiculous. People have been trying to get the Second Amendment removed from the Constitution since it was put there. Hell, people (Federalists...many of whom we deem our Founding Fathers) were avidly opposed to the entire idea of having a Bill of Rights in the first place. It's not going anywhere.