There are numerous excuses for not wearing a helmet: they are not cool, I don’t feel free, gives bad hair, uncomfortable, people I admire don’t wear one, real cowboys don wear one and so on. They are heard in every activity where wearing a helmet can reduce or mitigate head injury.
As bicycles are used more for commuting and loaner bikes are available, state legislators have gotten in the act for riders when they are on public highways. We need a community ground swell. The reasons for helmet use don’t change the use, nor does the importance of wearing one every time.
The trick to changing attitudes is to find the tipping point for the specific individual or group. A tipping point is the point in the system or process where a significant and non-reversible change takes place. The personal negatives of helmet use become unimportant and consistent wearing of one is an every time you get on a horse reality.
Find/engage role models. Use instructors and peers who wear and require those with them to wear helmets, accept parenting responsibility and adult modeling learn from knowledge of injury and devastation from head injury. Purchase only ASTM certified helmets and decorate them to suit your taste, helmets don’t have to be boarding. Be sure the helmet fits, figure out how to keep it clean enough not to be disgusting and wear it every time. There are no excuses.
The riders4helmets (LINK) discussion of several riders from many disciplines is worth a look.