Mountain climbers and skydivers experience GPE. You explained that GPE = (mass) (gravity) (height), and I agree with you that formula is correct. You then gave an even better explanation using someone on top of Mount Everest, and you said that the person's GPE was 7,370,384 J which is calculated from the height which is 8848 x the force 9.8 x 85 which is his mass. The GPE calculation is also different from someone on a ground since they have a different height.