Unfortunately you can't glance at a cyclist and decide affirmatively that they're an idiot for riding without wipeout skills.
You don't need that helmet until you do.
Let me assure you, if you've decided cycling safety is a binary contingent on whether or not you're wearing a helmet, you're doing it wrong. It's no better than superstition. There are so many other variables.
* Avoiding the crash in the first place
* Knowing how to fall if you crash
* Helmet, and potentially other protection, when unable to execute crashing properly.
(Edit: Changed ’security’ to ’safety’)
I got three stiches in my chin. I lost two teeth; one was driven through my lip, and I had 13 stiches in that lip (there are three layers in a lip: outer skin, muscle, inner skin). I needed two root-canals. I fractured my mandible, which is now joined to the maxilla on only one side. I was concussed, and wound up sleeping about 15 hours a day for the next 3 months. I couldn't chew for ages.
A motorbike helmet might have helped; but not a bicycle helmet.
Of course, the helmet is only 10% of cycling safety. But it's for that important 10% when your head crashes into the ground. Suggesting that it would never come in handy is naive.
Since you seem to believe in the power of personal anecdote, I am an experienced cyclist and have crashed directly on to my head before. It was just once, but it prevented a serious head injury.
We went through this same nonsense with motorcycles. Stop acting like it's the end of the world to put a piece of foam and plastic on your head for a little bit.
If someone asked me to wear a helmet while running, I would find that ridiculous. Same thing when riding my (non-road) bike.
Bike speeds > 20km/h are normal and easily achievable for the untrained on flat ground. Downhill, you'll quickly go past 30km/h. This isn't something that you're doing while running for longer periods of time while you're still half-asleep.
Helmets annoy me too, but "the fastest runners can peak at speeds higher than what I reach every other day on my bike and they don't wear helmets" is a weird argument.
For rides where I go faster, I will take my road bike and wear a helmet.
For rides where I go slower, I would prefer not to wear a helmet, but mandatory helmet laws don’t make that distinction.
As you alluded, even between bike trips, I weigh the risks differently when I think about a casual spin down a protected lane or a recreational trail as compared to an aggressive commute inches apart from vehicle traffic.
My local bike share program has started blurring things even more for me lately as they introduce progressively zippier e-bikes. Any more, it’s trivial for me to move with traffic on these huge heavy clunkers of bikes, while to my impulses it still feels like the low-effort casual kind of ride I’d instinctively rate as not warranting a helmet.
Still, I’m glad to be judging for myself how to mitigate the specific risks of a specific ride.