I find the benefits of not wearing a helmet to be: * Deciding to cycle for short or leisure trips is lower friction (I always wear street clothes, too.) * I can hear better. * I find myself more careful about intersections. * Motorists seem to give me more room. * I have one fewer item that can be stolen. —— On the other hand, I find the helmet benefits to be: * My head is better protected in a crash. * I feel more c…
* Wearing a helmet only protects the head from a limited number of possible injuries.
* Wearing a helmet makes people overconfident and overly risk-taking.
* In the Netherlands, very few cyclists wear helmets because they are experienced by cycling almost daily, don't take unnecessary risks and street traffic design is far superior.
* Wearing a helmet looks dorky.
* Wearing a helmet is proven to cause vehicle drivers to respect bicyclists' space less, leading to more fatalities and injuries. [0,1]
0: https://www.bicycling.com/news/a25358099/drivers-give-helmet...
1: https://road.cc/content/news/252652-study-still-indicates-dr...
Conclusion: A helmet is unnecessary for experienced cyclists who are only going 10-15 km/h in proven safe traffic-designed areas, all other use-cases: it depends.