If you choose not to wear one, statistically you are still more than likely to have a long healthy life. I'd guess longer than if you didn't cycle at all! Personally I didn't ride with a helmet accept to race (a leather hairnet then) until the early 1990's and still take it off for long hot climbs unless local law says otherwise... I'll accept what I feel is absolutely minimal risk. Oddly, everyone I know who was cycling at that time is still alive. Same with skiing. That said, risk mitigation is your choice. Helmets help, but they aren't a personal force field and don't do much for high speed impacts with immovable objects or protect your legs/spine/neck/face/teeth/internal organs. That's where the "make choices like you're not" comes from.