You're UK right? You might not fully understand the reason we have the second amendment in the USA. In addition to the defense of our families and homes, we have the right to bear arms to resist and overthrow a tyrannical government if/when all other checks and balances fail. Nobody is hiding behind hunting or purely home defense against a single unarmed burglar. It is more of a deterrent at the current moment, but if the government becomes unstable the citizens have the capability to re-organize.
As far as home defense, the more wealthy you are, the bigger target you become for professional armed robberies. If you want to be naive and plan to call 911 that's your choice. I can't afford to wait if someone comes in my house trying to steal my wealth or hold my family hostage. This shit is real; it's not just in the movies. If you think I'm exaggerating, then open your mind and educate yourself by looking up real attacks on homes over the last 20 years. They don't usually get media coverage so it's more difficult to stay informed. Mass shootings get media coverage because the broadcasts are profitable.
Anyway, while this subject has been debated constantly for the past 30+ years, limitations on firearms can only go so far. First, there are millions of unregistered firearms that laws do not affect. Second, if the government attempts to mandate a ban on firearms, there will literally be a civil war. The citizens aren't going to turn in their weapons.