If you think its good that only the police (good guys) use guns, imagine what would happen when a dictator like hittler shows up and turns the police against your whole town and way of living. What do you do then?
Let me set up an arguement for you.
A. Guns will never disapear from society
B. If you make guns illegal only people who want to do illegal/immoral things will find a gun.
C. Therefore, the right to protect yourself against criminals/invaders/military state/ so on and so forth, becomes broken.
This is exactly what you see in the middle East and Africa right now as we speak. This is why people of those countries get trained from our troops, get a gun, and protect them themselves from those insane monster squads trying to cause terror.
In America, now that people have the right own guns. We don't deal with that type od BS in our country.