Like the GP (and most people, I assume) I really value my mental faculties, but more relevant in my opinion is that in terms of time and often money, your collective knowledge and education is probably the most expensive thing you've invested in. To not do the bare minimum to protect that investment is incomprehensible to me.

My friends will buy ergonomic keyboards, standing desks, monitor arms, etc. to keep them healthy and productive (which is important), but not wear a helmet because "they look dumb". Without a working brain, none of that other stuff will matter! I always ask them, 'Are you expecting to find a partner while you're on the bike? Who are you trying to impress?'