Of course I may crash on any given ride - I make no bones about it. I may stumble on the sidewalk the next time I walk out the door, fall and bash my noggin. The only reason I won't wear a helmet walking out my door is the low probability of that happening.

It probably won't happen that I crash again on the streets, but there is a chance. If I do crash, I probably won't hit my head but there is a chance of that also. If I do crash, and I did hit my head, it probably won't be more serious than cut or scrape, but there is a small chance of that also. Multiply these three probabilities together and that's my risk when not wearing a helmet. From the best information that I have available, multiple studies for which I do have the background and am qualified to evaluate, I judge that number to be very small for me individually.

What I'm asking of you is your evaluation of your risk. Do you think that it's inevitable that you'll crash, and when you do it's certain to be a severe impact on your head? It seems like that's your reasoning, but if not then about how much more likely does it have to be for you than the risk of walking down the sidewalk?