Guns are specifically designed to kill people. That's why they were invented, that is why they are constantly being improved. And the gun companies are introducing deadlier weapons every year.
This is pure ignorance on your part. Guns are designed to fire bullets. Many bullets are designed to injur, though not all. Though again, at the end of the day, what someone else intended for a gun to do is entirely irrelevant. I ultimately decide what it's going to be used for. Despite what you say the fact that the vast majority of firearms in fact are NOT used to kill people proves you wrong.
There is no good reason for an average citizen who is not involved in security or law enforcement to have a gun.
I don't need to have a 'good' reason (an entirely subjective statement in the first place). Need is an irrelevant argument. We don't live in a society where we're only allowed to posses the things we need to survive. Given the statistics on gun related injuries and death compared to other things you seemingly don't have a problem with it is the reverse that is true. There is no good reason I should NOT be allowed to have a gun(s).