I grew up riding with nothing in my noggin than a cowboy hat :) it wasnt until I started riding english and agisting at places that I was required to wear a helmet.
We are supposed to wear helmets at the pony club to but I only do when there are other people there who will tell on me lol
To me when I first started wearing a helmet it felt unnatural. Id spent 15 years riding without one and when I put one on id feel constricted in some way. Its hard to explain. Im not good with feeling confined on any part of my body. Im slightly claustrophobic so I think that explains it. Even though I wear a helmet it is too big for me so that I can handle having it on. I know it wont do me much good if anything happens but I have to wear one so I do it this way. I know its not good and I know awful accidents can happen but I figure thousands of riders over time havent worn on and im sure that the incidence of a fatal head injury is much lower than the number of people who have ever ridden without one.
Plus like someone else said, I live in a very hot climate with major humidity. Even when its not hot its humid and I don't deal well with sweating that much. I get run down and feel sick very easily if there is something on or around me that makes me hotter.
So like AK im probably too stubborn and silly for my own good but hey, if im going to die im going to do it coming off a horse. I guess its easy to get complacent to when you havent had a buster in about 11 years and only roughly 4 falls in my whole life. I know pride comes before a fall but im on a good wicket at the moment
Having said that, its my choice to not wear one so I am not telling anyone to go riding without one. Its just the way I work :)