Is it a "spectrum thing" to be totally petrified of roller-coasters? For the longest time in my childhood & youth, I was really afraid to go on rollercoasters, even the "tamer" ones - I was so afraid that I didn't think I could conceal my fear in the line-up right up the embarking point, where staff would undoubtedly ask me the familiar repetitive question: "Are you alright? are you gonna be alright?? ARE YOU SURE???" and then being left embarrassed as heck, and the fear of THAT embarrassment getting to me also.
However, I did "conquer" my fear if you can call it that. When I was 16, I went on my first roller-coaster, at Canada's Wonderland in the Toronto suburbs where I lived. It was the Wild Beast, and I believe it's still there today. It's moderately scary. Later on in my late 20s, I went back there with a girlfriend who really wanted to go on the Top Gun thrill ride, which goes upside down - something that scared the heck out of me (maybe due to sensory issues), and she noticed I was a bit nervous but I had to "be a man" about it and steel up my nerves, which I did...and I went through it, but closing my eyes most of the time. I did it a second time (on a second visit, as I don't think I could have done two of them in the same). Then I also went on The Vortex, which was really steep and scary. However, I would NEVER consider going on one of the insanely tall and long rides, like Behemoth or that "Kingda Ka" one in New Jersey, and I'm sure there's some 300-footer or something in one of those places like Six Flags Texas or Cedar Point.
On a humourous note, I likened my little predicament to that of Rain Man where I could've imagined myself compiling stats on all the rollercoasters and theme parks that had fatalities, and the only one that didn't was in Australia But don't get me wrong, I do think about it more logically, that statistically you are far more likely to get killed driving to the theme park by some idiot talking on his cell phone thru a red light, than you are to get killed on the coaster. And I certainly didn't worry myself driving to the theme park. That's why I found my reaction (and Rain Man's) to be a bit of a paradox for people on the spectrum.