Imagine you are in a room with 90 people and one gun. Your gun. You don't plan on murdering anyone but for some reason you decided to be an idiot that day an accidentally fired it. The round scares people but luckily misses your foot and hits the ground causing minimal injuries from shrapnel. You live they live everyone goes home.Well you might be going to jail but that's not important right now.
Imagine now you are in a room with 90 guns and 90 people. Your gun and 89 other people carrying a single gun. You don't plan on murdering anyone but for some reason you decided to be an idiot and accidentally fire the gun. Immediately a trigger happy person in the room shoots you in the face because they thought you were firing in their direction. It might not happen. You might still live to be a huge idiot. But the worry is there. You are more cautions about accidentally or purposefully firing a weapon around other guns. Unless you are a suicidal terrorist with no regard for your own life. More guns equals less violence.