Greg is afraid of being carjacked and other violent crimes. As he pointed out, criminals have guns. If some guy just shot my wife and was aiming at one of my kids, you bet I'd rather have one of my guns in my hand than a cell phone or pepper spray.
I may write to Greg in a joking way, but if Greg is serious about his fears, he needs a gun. I don't know how he sleeps at night. He also needs hours of training and many hours more of shooting practice. There are areas of this world this aren't pretty. If he has a job that takes him to those spots, perhaps late at night, he needs to protect himself.