I must say when I took a hammer to an old helmet it took a lot of hard whacks before much happened.
I dropped one (around £ 30.00) from handlebar height, a big chunk detached itself.
Another helmet, quite pricey for me at £ 70.00 rolled from my hands at pannier height, dented.
I'm not buying another one, waste of money, keeping the dented one in case I need to wear it for events.
But back on topic. I've seen a lot of folk who I know were more biased towards longer distance / road riding, and exposing themselves to the added risks involved in such riding, have had enough of it, and only 'leisure / utility' ride now. A lot of them no longer think that the risks they are now exposed to, warrant wearing a lid.
That is a bit silly, you can come off or be run over if you are on a utility ride.
Group riding is of course more risky, specially at fast speed, but on our paced ladies group rides there has been incidents too, due to too much chatting, no enough concentration on the terrain.
The bloke wearing one backwards, well what can you say...
80% of the helmet wearers I see have it fitted wrong.
I'm not wearing one unless I have to, or if the weather is really bad, gives me an extra layer of insulation.
Did not think I needed one when I started cycling, then caved in to peer pressure.
If they break by being dropped 50cm, what's the use?