I think people who have started riding within the last 10 years or so are more likely to wear a helmet all the time

some of the young fellas down at the LBS say they just always wore one, so they don't even think about it

but 20 years ago adults never wore helmets, so for better or worse, there are alot of people who have ridden for 20 or 30 years or even more who prefer to ride without one

I ride both ways. I wear one alot, but I also like some days to just wear my old cycling cap for old time's sake. sort of a nostalgia thing