I must disagree with your first premise. I am 64 and love the front seat of coasters, looping upside down and twisting in spirals. I especially love the first drop, I love the feelings it evokes in my body, and I know LOTS of people my age who feel the same. So it might be more accurately asked, “why do most people” or “some people” but there is no objective principle at work here, just the individual’s experiences and associations. That’s why you have senior citizen skydivers, etc.