The wearing of bike helmets is evidently a controversial issue.
Some years ago I rode motorcycle escort for the Seagull Century event from Salisbury State University in Maryland. We were warned that toward the end of the 100 miles ride, cyclists will be tired, and there would likely be accidents. In the last couple of miles, several riders were drafting when one of their front wheels touched the rear wheel of the guy in front. I was right there and the thud he made when he hit the ground was sickening. He was unconscious. His helmet had hit the road, tilted to the side of his head and he hit the road again. opening a big cut in his head. I think that had he not worn a helmet, he might have been in a much worse condition. At least it took the initial hit.
I prefer riding alone, and I rely on observations more than anything else. Twenty-seven years of riding motorcycles, and taking three Experienced Rider Courses over ten years, helped me to be aware of things that some cyclists might miss. I don't assume anything about car drivers but I do anticipate their moves. I'm quite aware that my baseball cap won't do anything to protect me in the event I should hit something or take a fall, but it's my choice. The biggest problem I see with many Florida cyclists, is that they tend to wear dark clothing, even at night, and have no lights on their bikes. I read of more being killed while crossing a road then being hit by a car from behind. Carelessness probably accounts for some of the crashes.
One last thing: A few years ago, just before sunrise, I hit someone's ridiculously high homemade speed bump. I went over the handlebars and landed on my chest, but my head didn't hit the road. I lost skin from my elbows and knees, and got a couple of cracked ribs. I guess it depends on how we land when we take a fall. That taught me not to assume a dark road is without obstacles. My cheap bike light, at the time, was little more than useless.