I work at a resort that doesn't require helmets.
Everyone keeps posting how helmets are only rated for low speed accidents, somewhere up to something less than 20mph; round down to 15mph. The next statement is that you ski faster than that. Let's say 30mph on average. I know many folks ski much faster than that but it seems a good place to start.
The statement that I haven't seen (maybe I missed it) is what speed is your head rated for? I'm talking can handle the impact with nothing more than a lump; no concussion, no unconsciousness. A little blood is OK but no stitches. I believe most of the non-helmet wearers believe it is the same as the helmet rating <15mph. I
Since I've only done Math for Marines, could someone else compute if you hit your head at 30mph with a helmet on rated for 15mph, what will the net impact to your head be? Will it absorb 15mph worth of impact leaving you the effect of an impact to your head of only 15 mph? I have no idea how the math works but at low speed or high speed, it's going to absorb/displace some amount of the energy.
I don't care if you're swinging a wooden baseball bat fast or a wiffleball bat slow. If the swing is coming at my head, I'll take a ski helmet over thin gray hair any day.
I don't even think I wear it so much to protect me from falling as I do to protect me from everyone else.