A gun is designed and intended for one purpose: Killing. It has no other uses, unless you’re Homer Simpson.
And it allows the user to do so with minimal effort and consideration—and from varying distances.
The accuracy depends on user skill, but also a great number of other factors. Unlike a knife, which must be used at close range to the target, a gun can be fired at the target from a distance and if is misses—or even if the bullet hits the target—it can also potentially hit others who are not the intended target.
A bullet is far more likely to kill than a knife.
Some legal firearms can be used to kill multiple targets from long-range with minimal effort put into aiming (see Las Vegas).
There are only two legitimate reasons to own a gun: Sport and defense of livestock from animal predators. Any other reason—when you eliminate all false claims and statistics by gun advocates—is far, FAR outweighed by the risks to human life.
Banning guns except for the two reasons mentioned above, regulating for those two reasons, and eliminating political influence of the industry on government would save tens of thousands of lives every year.
It’s the biggest no-brainer of any issue in the US, yet we let the greed of the industry and the fear of some of our citizens hold everyone hostage.