Ok, here is probably the only treadmill I would be interested in using:
The Virtuix Omni™ is a first-of-its-kind active virtual reality motion platform. Active VR, where your actions in the virtual world are controlled by first-person navigation like walking or running, creates an unprecedented sense of immersion that cannot be experienced sitting down. The Virtuix Omni™ lets you walk, run, sit and strafe with 360-degree freedom of movement allowing you to control your avatar without restraints.
Check out this video showing it in action:
Even more interesting, you can invest in the company is a venture capitalist here: https://www.seedinvest.com/virtuix/series.a
Virtual reality is going to be a huge market soon, might be time to jump into some of these up and coming companies.