I never felt sick from just VR, but the continuous movement (rather than teleporting) made my brain confused like I wanted to fall over, but after a few hours of it I got used to it for good and now have no problems with VR, other than fatigue of moving around so much aha.
I think most people could break it in, but are reluctant to keep playing or play again once they feel sick doing it. While its easy to get immersed, you have to disconnect yourself from it a bit and remember you are in the real world, when friends and family try it I have to make sure they dont walk into walls, but on my own I have full awareness of my surroundings even when I am blind to it. It just takes time to get used to it.
It's a really fun experience, I hope it keeps getting developed regardless of sickness issues. Higher framerates are definitely important, the 120Hz mode on the Index is definitely recommended, any lower and its much more likely to be sickness inducing.
I think most people could break it in, but are reluctant to keep playing or play again once they feel sick doing it.
The article author reports trying twice: first a rollercoaster, and then a racing game. Then cites a study about people getting sick in their first 15 minutes of use.
I think you're right, but some people just aren't going to give it another try. I think this tech is likely to be one of those big generational dividers that old people just won't tolerate (like computers or cell phones, or the thousands of prior things).