I wear a helmet to mainly protect my head from scrapes and bangs from dense singletrack (branches etc) and general knocks from messing around on the bike. The peak also helps protect my eyes along with glasses. In 20 years on riding I’ve crashed many times; I can’t say whether the helmet stopped me from drinking through a tube right now. All I know is that the last big stack I had if there was no helmet I wouldn’t be here. High speed, head first (top of the head) into a pointed rock. The helmet had a inch and a half hole in it just stopping short of my skull.
It is about risk assessment and if people don’t want to wear them then fair enough. I’ve just got into the habit of always wearing one.
Plenty of guff on the internet, anti helmet wearing forums etc give negative feedback from wearing and obviously pro-forums give the opposite.
The danger is slightly increased with the speed and type of terrain on a bike. People don’t walk down the streets with a helmet on – they can easily trip and smack either the back of their head or side of the head on the kerb/pavement and die.
You will always get people banging away on a different drum beat anyway.