A guy I know, a bit of a local legend, in fact, used to ride without a helmet. He was super strong and loved to take pictures, and would post them on Strava and IG, which shows him sans helmet, solo, of course. Last year he had horrific crash, but fortunately had his lid on, and man, the damage to the helmet was just unbelievable! He survived it.
Having said that, I sometimes ride around the neighbourhood on my old mtb without a helmet for groceries and coffee, and such, or with the kids on the trails. But I always wear a helmet when riding solo on my road bike or with a group.