I got this second hand, but I believe it. A survey was done at a high overlook and roughly half the people who stood at the rail thought about what it would be like to step off the edge. Not planning to, just thinking about what it would be like. I know I do in that situation or similar ones. I have no plans to do it. I have a very strong survival instinct and have never made plans but I have thought about what it would be like; what must go through someone's head while falling from a great height.