It's true. But it can and does kill fit people occasionally too. Some 25% of people are genetically predisposed to altitude sickness above 4000m according to a

It's true. But it can and does kill fit people occasionally too. Some 25% of people are genetically predisposed to altitude sickness above 4000m according to a researcher I met while walking that trek myself. Base camp is well above 5000m. Amazing trek though. One of the greatest experiences of my life.