Seatbelts are a terrible analogy. You wearing a seatbelt affects no one else.
Firearms are more like using the "PIT" maneuver to spin cars off the road when they present a danger to you, except that's slightly less likely to kill someone than blasting them with a gun. In this analogy, it's ok to run someone off the road because they drove unsafely causing risk to you and your family. It's true - you can die because of other drivers, and it can be totally unexpected. Similar to your attack fantasy. So why not be able to PIT someone when you see dangerous driving behavior? What are the pros and cons? Does it make sense to do so? Does it make you safer? What about others on the road?