63. Your friends pass you by.

For graduate students, nothing drives home the fact that graduate school delays adulthood (see Reason 12) more clearly than observing friends who choose a different path. You may enter graduate school with the belief that an extra degree or two will give you an advantage in life, but while you are concentrating on gaining an advantage, your friends are concentrating on life. They may never turn into millionaires—though that is far more likely in the real world than in the academic one—but they probably will pass you by. While you sit in a cramped living space working on your dissertation year after year, your friends will be working hard, too, but they will be earning salaries. They will also be buying cars and houses, getting married, and having children (see Reason 15). They may even take an expensive vacation or two. It can be hard to relate to old friends who live in a world increasingly different from your own, and even harder to make new ones (see Reason 50).

This is about more than keeping up with the Joneses—or counting on catching up with them after you finish your education. The lives of your friends are reminders of the true costs of graduate school, which can be much higher than you anticipate. More than a quarter of women in their early forties with graduate or professional degrees are childless. After years of graduate school, will what you have gained be worth what you have missed?