Now, what happens if you simply get off the treadmill? Now all your walking efforts go towards moving your forward, and if you stop, you just stop - no regression.
I think for many the fear is not having the direction and certainty associated with the treadmill. Navigating on your own without any systemic aid or structure can be pretty scary, but from my experience, it is worth it.
A step at a time.
That's a great point!