Sounds like the comfort level has something to do with the amount of time spent at that altitude. Instinctive fear is there to keep you alive. The greater the height that you fall from, the higher the odds that when you hit the ground the deeper the hole that you'll create is going to be. That fear can be overcome with exposure for most. My toes try to reach back and curl around the rung of a ladder at any height greater than 6 feet to the extent that I can hardly walk when I climb back down. I just don't happen to spend much time on a ladder. When flying, the higher the better. Glide ratio in fixed wing was burned in to the gray stuff behind my eyeballs early on. Near miss with an unmapped power line in a S55A and attending the funeral of a buddy that did not miss a powerline a couple of years later added to that desire to be up high. Probably sounds odd, but a man that can't climb a ladder without experiencing physical pain is perfectly comfortable at a height which if he fell from would certainly result in the "nuthin left but hair, teeth and an eyeball" scenario.
No powerlines at 5k AGL.
