Steve Levitt reports:
They find that each extra close friend in high school is associated
with earnings that are 2 percent higher later in life after controlling
for other factors. While not a huge effect, it does suggest that either
that a) the same factors that make you popular in high school help you
in a job setting, or b) that high-school friends can do you favors
later in life that will earn you higher wages.
Read his caveats as well. I would like to know more about the shape of the distribution. I would think that the most popular people achieve only mediocre results, whereas the very high earners are either loners (but not necessarily “unpopular” in the sense of being disliked) or had above-average popularity but not extreme popularity. Too much popularity too early produces the feeling that other things will come easily, too easily.
Personally I still receive benefits and favors from high school friends and I once wrote a book with one.