I explain gun ownership and carrying to be similar to locking your doors at night or wearing a seat belt. Neither locking your doors nor a seat belt is a guarantee against death anymore than a gun would be, but if you are at an ATM with your kid in the car 8ft away, wouldn't you want some reasonable protection against being carjacked, kidnapped, raped or murdered? Is it likely? Of course not. Is a gun reasonable protection? Just as reasonable as wearing a seat belt in the unlikely event you are in a car wreck. That's how I try and verbalize the "reasoning" to someone frightened by a paperweight.
I wouldn't recommend everyone who can operate a seat belt own or carry a gun and the "menace" associated with guns is a little childish in the 21st century.