I can understand, I’ve had some awful bicycle accidents while not wearing a helmet and the helmet would have made no difference. My knees, hands and elbows have been through a lot but I have never hit my head. Even while skateboarding the one time I hit my head a helmet would not have helped. In hindsight I should have worn knee pads a lot more often but then I wouldn’t be able to tell if it’s gonna rain or not from the feeling in one of my knees :)
However if I had to ride on a public road with cars zooming pass me recklessly I would absolutely wear a helmet on a bicycle.
And there are countries where everyone rides a bike, and they are not usually the ones with mandatory helmets. When you hit someone with a bike you are less likely to kill them than when you hit them with a car, so more bike riding means less deaths, without even considering the effects of air pollution.
Helmets are fine for sport riding, but inconvenient if you want to ride 5 minutes to the shops on a whim. And that kind of riding is usually less intense and safer, I presume, anyway. Football has helmets, walking doesn't.