I think people just need to try it once and see how you react. If you have motion sickness, take a pill before (my preference is Bonine). I also went on about an 90 mins after having lunch.
The only ride that has ever been a one and done for me is Mission Space Orange. Everest, I can go 2-3 times in a row - but then I'm pushing it, there is one part that always like clockwork I feel in my stomach. Teacups ... I just don't do it. Last time I did - I tried to make it not spin
GOTG I was fine - we were in Row 9 - which becomes Row 1. I was only able to go on once due to AP Preview. Going again in September, so I'll know for sure if I'm really OK after going on it more.