Seat belt laws are about the first responders and general public when crashes happen. I agree it isn't really about your personal individual safety though that is how a politician or many others spin such policies. The system of public policy like first responders do not want to impaled bodies needing to be pulled down out of trees, pulling bodies off of steering columns upon which they were impaled, or shoveling them up from the roadway after they are slide across the rough pavement which acts as a cheese grater. The first responders do not want the mental trauma/haunts of such visuals which were common before seatbelts, and nor do we want such haunts/visuals for the general public which witnesses crash scenes from time to time.

Funny fact is when seat belts were introduced auto crashes went UP... so you could argue they lowered personal safety in that one sense. Seat belts provided a feeling of safety so people were less worried about getting into a crash so they drove more risky/fast/fun. When people knew you could be thrown clear through the windshield IF you crashed or impaled upon your steering column you drove a lot more carefully than people do when knowing are strapped into the seat. They also didn't have safety glass originally so going through your windshield was likely to decapitate you or slice you to bits.