I'm not trying to rain on your parade....but, I think you'd find MOST people terrified of venturing out on such structures.
Just for fun, what's the highest such example YOU can find which now exists...???
I don't know if this qualifies, but the bridge is 44 stories up. It's over 150 feet long and people wait in line for hours and they have to give out tickets to manage to crowds. Sounds like they aren't too afraid. I imagine the cost of building them is why there aren't too many around.
I once leaned over the edge of the roof of the John Hancock Center in Chicago to take a picture straight down to the street. Held the camera in one hand outstretched, pointing straight down. The other hand outstretched in the other direction, holding onto the window washing rail.
Unfortunately, I didn't know until later that I had not properly threaded the film onto the takeup spool, so I didn't get any pix.