Earlier quoted context omitted.
It sounds like you're not informed. https://www.vox.com/2014/5/16/5720762/stop-forcing-people-to...
> Helmet proponents are right about one thing: If you're in a serious accident, then wearing a helmet makes the odds of a head injury significantly lower — by somewhere between 15 and 40 percent. (This is why ER doctors and brain surgeons are so pro-helmet — they've seen firsthand what happens in helmet-less accidents.) So this is why most of us wear a helmet. The logic is not "so few people get in accidents that if…
The person who is truly taking a risk is the person who doesn't ride a bike because of the perception that it's dangerous, and continues to be sedentary and drive a car to work. This person is literally reducing their life expectancy by years. (See links I posted elsewhere in the thread.)
You need to be able to think about conditional probability.