All of my coworkers, and many of my friends carry guns most of the time. My observations are that it really does not make them or society any safer. In fact it only makes a gun available to the first criminal who is strong enough to take it away.
Law enforcement officers (LEOs)are way too slow to shoot making them vulnerable to having their guns and lives taken. Non-LEOs are generally too slow and unskilled to be effective. And rarely do they take into account “whats behind the target”. Making their using a gun dangerous to bystanders.
Many bad guys have spent years in prison studying how to disarm citizens, lifting weights and to attack with such speed that even the best trained armed people are at risk.
21 feet is the magic distance. A skilled criminal within 21 feet, can probably kill an armed person before he/she can draw and fire.