I'm not so sure about that. Some careers are simply known to be very stressful - for example most transactional work (investment banking, corporate lawyers, accounting consulting). It is self-reinforcing in the sense that each company has to keep up with the competition, but I believe that would happen regardless of the level of stress students experience in school. Personally, I have managed to avoid such environments, but for some people, that's the easiest, fastest and least risky way to success.