simple thought experiment: You are carrying a gun. Someone else decides they want to do something dangerous with a gun. (shoot some people; commit a gun-crime, etc.). They know they are about to become a target because everyone else is usually also self-preserving. They decide to shoot anyone with the means to slow them down. That primarily includes everyone else with a gun; anyone else strong enough to overpower them, and anyone able to alert authorities on them.

Who do they shoot first? anyone else with a gun. Likely a not safe position to carry a gun