I mean, they are empirically recorded to lessen the occurence of critical head injuries in the event of a crash resulting in head injuries, but what chance any given cyclist has of experiencing such a crash remains the same and depends on their riding environment and riding style, so whether they consider helmets a worthwhile peace of equipment is up to everyone to decide for themselves individually. I'm never gonna wear one on my commute even though it makes up most my annual riding by distance because I don't feel at risk and consider it too inconvenient all things considered, but I would wear one if I was doing road ridng or downhill mountain biking.
