[D_Alex]

"extremes are bad"

I disagree, a little. Extremes are good, because a bunch of worthwhile things get accomplished by people going to extremes.

As far as personal costs of going to such extremes go - they are difficult to judge objectively, from the outside. A study I recall claimed that elite athletes are "happiest", based on self-assessment, and it further speculates that one reason for this is because they have a clear goal and a clear way to advance it.