I'm from the UK. I've heard many of the arguments on both sides, but to me nothing is more convincing than the statistics (example: http://www.bbc.co.uk/news/world-us-canada-34996604). I'm also a libertarian, I fully understand that if anything a right to bear arms is needed because any other way is a breach of personal liberty. However, I can't help but see that as a negative side effect of full liberty, because inevitably it just leads to more people getting hurt. That's the numbers talking.
Yes, cars also kill people, but I don't need a gun to get to work. The benefits of having cars in society vastly outweight the drawbacks. With guns, the only benefits arise when a really tough intruder is in my house or when the government is trying to oppress me. In the UK we still manage to survive a break in without shooting everything in sight, and if the government came after us, they'd likely win even if we had a gun.
As the saying goes, there are lies, damned lies, and statistics. Reality is far more complex. For example, between 1993 and 2011, gun-related homicide dropped by 39% in the US,
despite the fact that gun ownership is higher than ever(EDIT: Commenters have pointed out that while the total guns owned has increased, the rate of ownership has decreased.) (This has coincided with an overall decline in crime which most people aren't even aware of.) I'm not necessarily suggesting that more guns caused the decrease in crime, I'm just pointing out that more guns does not mean more crime.The causes of crime are far more complex. The U.S. has countless other problems that are different in other countries (War on Drugs, gang violence, cycle of poverty, etc.). This makes it especially difficult to compare crime levels between countries. Switzerland has very high gun ownership (30-60% of the population), but their murder rate is half that of the UK. There is also the oft-cited example of Chicago, which has a notoriously high murder rate, despite the increasingly stringent gun control measures.
I understand that this might sound like a nutty-American thing, but we're serious about the idea of "inalienable rights." The Constitution doesn't grant rights, it protects them. It's not contingent on the "benefits to society." I realize this might be hard to convince you of, but it's how a lot of people see things here.
In the case of a break in, would you rather have a gun or not have one? I don't own a gun, but in that scenario, I'd rather have one.
Regarding the idea of defending yourself from government oppression, I get that you and I live in two of the most stable governments with the most powerful militaries, so it doesn't seem important. However, the general idea of an armed rebellion in response to a tyrannical government shouldn't be dismissed. A cursory glance at the recent history of the Middle East shows how much trouble armed rebellion and militias can cause for a regime.
Also, if the government came after us, they'd likely win in any scenario. But the kind of government that would use military force against its own people is exactly the kind of government that should be overthrown. If that happened, I'd much rather have an armed population.
EDIT: Wow, thanks for the gold!