Read some of Massad Ayoob books on calibers and stopping powere.....
"A large guy tried to shoot a police officer on a routine traffic stop. The officer drew his 40S&W loaded with 135jhp and fired one shot. The bad guy dropped and was clinically dead 10 seconds after the shot. The corroner called the police department and asked what explosive charge was inserted into the bullet that was used". The 40S&W brings more to the table than a 9mm. That's not to say a 9mm isnt effective but big and fast is better than smaller and fast.
"I'm a good guy with a gun" What do I care if I give up some freedom or rights?....The Goverment will take care of me. This kind of thinking is now in the majority and it should concern you.
"Ask not what you can do for your country, but what free entitlements you can bleed from your country"