Nothing guarantees that you will not be "killed in the street", but having a gun puts my life in my own hands. Sitting behind a desk, behind a door, in a building surrounded by armed security, politicians think they have the right to strip you of your ability to defend yourself and tell you to rely on the police for your protection. You're right.... a gun will not prevent you from being killed in the street, neither will a cop.... or a "gun free zone" sign.....
It's not about guns preventing crimes, it's about each individual person having the right to defend themselves.