Because doing stuff from the tops of mountains is very difficult. The logistical complexity and cost of doing something from the top of a mountain swamp out the

Because doing stuff from the tops of mountains is very difficult. The logistical complexity and cost of doing something from the top of a mountain swamp out the comparatively small advantages. Also, the best places to launch from are near the equator where there is a large body of water Eastward. And there are very few mountains in such spots.