I currently visit a theme park with some friends. There I noticed that I am highly afraid of rides that involve heights and fast moving like roller coasters. We rode a few of them, and of course nothing happened, as it is supposed to be a lot of fun. But for me it is more like a constant situation with fear of falling.
Empirically I know that the park has been around for a while, that very few accidents happen, and that there is no particular reason to actually be afraid. The park makes its money by offering its rides to many visitors, and they really seem to know what they are doing. So why am I afraid? In the past I ONCE had an issue with my non-standard height being a minor problem. But I routinely check the size of other visitors, and the rides seem to be designed in a one-size-fits-all-unisex way that works for all shapes and forms there are.
I am also somewhat afraid of heights in general, which for the most part serves me pretty well. Should I turn that off while in a theme park? Is it reasonable to not ride the roller coaster?
There is probably a design principle in rides that elicits strong reactions in the user. And I am not sure if I would want to self modify to actually enjoy the ride. But being afraid seems also pretty useless. It is not rational.