as others here have said, you may never need. but just once, it is worth it.
why have auto insurance? do you want to use it?
in my 3 decades of driving a big rig only once i wish i had a gun on me.(company says fired if you have anything like a weapon with you) and that was in fresno, ca. and yes i have been in some "shady" places.
but the only time you may ever need to shoot something would be at a pit viper.
it comes down to you, are you ready to take everything away from somebody?
(that crook is).
if not then carry a none deadly device, and pray for the best.