In the 1978-84 range when I was at my most stupid, we pretty much didn't know that helmets even existed. Well, other than borrowing my buddy's big brother's motorcycle helmet to ride around the driveway for a few minutes. Had I been sporting one for some of my more spectacular crashes, I'd probably be 20 IQ points higher.
Personally, after seeing firsthand the effects of head injuries for the last 20 years, I'm glad that we have decent helmets as an option now.
(And the dude jumping the fire should really have Nomex jeans and hat on
)