I don't think de Button mentions anywhere that status is based on merit (which is good because the correlation depends on many factors and is tenuous, at best), or what you have achieved.
He's saying that your therapist might ask about your parents and family, but won't probably ask about the nameless people you run into every day -- your neighbors, the people in line at the store, etc. -- but these people also play a large role in terms of your self-esteem and ultimately your happiness because you are constantly defining yourself in terms of those around you. You will be happier living in a place where you make 10% more than the average, than where you make 10% less, no matter what that amount is.
He's saying that your therapist might ask about your parents and family, but won't probably ask about the nameless people you run into every day -- your neighbors, the people in line at the store, etc. -- but these people also play a large role in terms of your self-esteem and ultimately your happiness because you are constantly defining yourself in terms of those around you. You will be happier living in a place where you make 10% more than the average, than where you make 10% less, no matter what that amount is.