I guess if I was a pedestrian who was unsteady on my feet for reason of some infirmity or other, I would consider wearing something, or using a zimmer to protect me!
In any other case, I accept a certain amount of risk, for a greater amount of "freedom". Everytime you open a tin of food, you accept a risk that it might be contaminated. The reason you accept it, is because botulism in tinned salmon is rare - but it is not unknown!
The greater the PERCEIVED risk, the more likely you are to take precautions, whether or not they are sensible!
Where cycle helmets are concerned, I wear one because it does not inconvenience me, it's not uncomfortable, it stops my bald patch getting sunburnt (I wear a hat in the sun even when not on a cycle), I have a cycle light mounted on it which lights up
wherever I look, AND, it
might just save my head from a serious injury - which protects my family from loss of a provider.
In other words, personal protection can be a family thing too. If you want to be reckless, your family might suffer. If you dont have a family, you might not think it so important.
Yesterday a 70 year old man died in Keswick, after falling from his bike in a side street, no other vehicle involved. He died of head injuries, and was not wearing a helmet. I'm sure that for a few days we will get a barrage of messages saying how important it is - but to my mind, at 70, the risks of death are starting to pile up from any number of causes, and I would have to say I would not wish to enforce helmets upon everyone, without first ensuring a whole lot more "risky" activities share the same degree of interference.