Two streets of 10 homes. Those living in the houses on 1 street are never permited to have guns, bows & arrows or baseball bats.
On the other street they are required to have at least one hand gun and one shotgun. The homes that have the guns are well known.
Guess which of the homes are more probably going to have robberies. Guess which ones are more probably going to come under assault.
Now, let’s change things. Still only 10 homes are armed but no one knows which ones. If you were a burglar, which homes would you choose to rob.
Logically, not many would take a chance to rob any. The 10 armed homes would effectively provide some protection for those not armed.
For this reason, I suggest it is advantageous to all that some are armed. If no homes are armed, all homes are subject to robbery, armed robbery or outright assault. In other words, that fella down the street with an AR15 or a 12 guage or even that .38 is helping to keep you safe, almost as effectively as that entire police department.