If you outlaw guns, only outlaws will have guns
There is a modern Adage that says....
If you outlaw guns, only outlaws will have guns.
The supposed purpose of outlawing guns (for everyone but certain privileged members of the government) is to take them out of the hands of those that would use them to Murder, Steal, Rape, or perform other forms of Coercion with them.
However, the problem is that people who would use guns to Murder, Steal, Rape, or perform other forms of Coercion tend not obey any government law (including the outlawing of guns), and end up keeping the guns they have, and purchasing guns whenever choose to (regardless of the outlawing of guns).
The net result is that only the people who would use Guns to defended themselves and those they care about have their guns taken away, leaving them defenseless.
Thus, instead of outlawing guns making "good" people safer, outlawing guns makes "good" people unsafe and tends to increase the amount of Murder, Steal, Rape, and other forms of Coercion... since these "good" people no longer have a way to defend themselves. And there is no longer a threat, of getting shot, to these people who would Murder, Steal, Rape, or perform other forms of Coercion.
Another Adage related to this one is....