Simple logic. If a mass shooter shoots people, it takes the police a while to get there and by then there is bad damage. But a civilian can stop it more easily since they are already there
Simple logic isn't proof. Simple observation and logic tells me that the Sun goes around the Earth. If you're going to make this argument, you need good evidence.
ITS BETTER TO HAVE A GUN AND NOT NEED IT THAN NOT HAVE ONE AND NEED IT; LIKE, BETTER TO WEAR A MASK AND NOT NEED IT, THAN TO NOT WEAR ONE AND GET SICK? THATS DIFFERENT