A helmet is a nice thing to wear when you are way past your prime like me, your bike is 25 years old and you can't remember the right technique to ride but nonetheless you are in the alps once more and going 60km/h down the hill. In this situation my helmet gives me the illusion i might survive this horrible idea.
When i'm riding to the post office to send you some of my old bike stuff to wear a helmet seems pretty useless to me. If i really get hit by a SUV i'm dead anyway. I got no illusions about that.
Talking about helmets another story comes to my mind.
I started snowboarding in 1989 and from one year later on i was working as a snowboard teacher for maybe a decade.
In all these years i saw maybe two or three kids with a concussion but despite training the right falling technique really every weekend some kid managed it to break its wrist. And even after we did info evenings for the parents that wrist injuries could be easily avoided with some protective wrist guards these same parents would keep on buying helmets instead.
I'm no snowboard teacher anymore but from time to time i visit my old school. And from what i saw the average overprotective parents today are investing their money not only in helmets like back in the days anymore. The kids today look like real soldiers in their full body armour. Hexpad underwear, back protectors and so on. The funny part is wrist injuries still seem not to be included in the abstract fears of these parents or maybe it is still not cool to wear some rollerblade wristguards during a snowboard lesson like when i taught one or two of these very same parents how to ride a board...
Helmets can help you to walk away from a fatal situation no doubt.
Mankind on the other hand seems to not be able to walk away from abstract fears. We learn and forget and learn again and forget again. We don't evolve unless we must and i guess nothing we can buy will ever change that.