While organizers are outfitting the expedition, mountaineers must make their own individual preparations for the climb because those who do not adequately prepare themselves for Everest often do not get very far up the mountain. More than 60 percent of expeditions fail to get even a single member on the summit, and it is not unusual to encounter people on the lower slopes who have suddenly decided to abandon an expedition, pack up their gear, and go home. The most common reasons for giving up are illness, fatigue, intimidation, and the loss of motivation.

The latter is particularly common on commercial expeditions, where amateur climbers are often surprised at just how difficult an environment Everest really is. Experienced mountaineers often complain that these amateurs are neither physically nor mentally fit enough to be on Everest. For instance, American climber Ed Viesturs, who has summitted Everest, said while...