This is a big reason why I skipped buying a OneWheel. They look like so much fun and I live near the beach where it would be easy to ride them on the sand. That said, too many videos on YT about them just randomly stopping and people going flying. I'll wait for other companies give them some competition in order to drive out better products (and lower prices) in the long run.
The real hidden danger of a One Wheel is if you're a non goofy footed rider in a bike lane. You're front is towards the side walk/parked cars, and your back is towards traffic in countries that drive on the right. I've been clipped by a car turning right who didn't see me and he was in my blind spot (directly behind my head).
There is actually a non Future Motion (Onewheel maker) maker of a similar device called the Trotter. It seems more companies prefer to make things in the ECU factor which is fair.
They don't randomly stop, they're just inherently dangerous unless operated correctly.
"Tech bro" Casey [0] [1] just did the NY Marathon [2]... he's not out of shape.
There are countless more videos on YT too [3] [4]. Heck, there are even little wheels you can buy to kind of try to help with the superman issues. Don't forget ghosting too.
No thanks. Enjoy your toy. I hope you don't get hurt.
[0] https://www.youtube.com/watch?v=5ay5M82IcUI
[1] https://www.youtube.com/watch?v=spdK6fAX0bc
[2] https://www.youtube.com/watch?v=7lGLhhoIsNc
Generally speaking if you don't have a background in boardsports it's probably safest to avoid powered boards altogether, no matter how many wheels they have.
The point, which you're glossing over, is that this is a new company, there is only one of them and they have some seriously dangerous and well documented issues with their product, beyond just using it.
Just like the OP's comment that I'm responding to.