wordfactory - I don't think that all high-achieving people are unhappy by any means. Just like I don't think all medium/low achievers are wonderfully happy! My post came across wrong if that's how it sounded.
I know many happy high-achievers, some in my own family. But, without exception, those people are happy because they are pursuing a career that they find intrinsically interesting. So they get satisfaction out of the job itself, as well as considerable financial rewards from it.
The high-achievers I know who are unhappy are the ones who don't enjoy the job itself. That can be extremely draining, to the point of actual depression. They feel trapped by the high pay, but IMO they are more trapped by the fact that they simply don't know what they really want to be doing - they haven't had the chance/taken the time to find their consuming interests in life, and they don't feel they have the power or the 'right' to follow them.
So, our plan for our kids is to help them find and pursue what interests them. I see no reason why they shouldn't get excellent grades in the process - but I won't be making the grades themselves the focus. It will be their interest and application that I focus on. I would never criticise a child for coming second in a test. But I would praise them loads for the work they put in, and have discussions with them about what they've been learning.
I'm not prejudiced against success! I don't mind if my kids are investment bankers, as long as they are happy ones. 