Not to be a jerk about it, but surely correlation doesn’t imply causation. A better explanation is that being <the sort of person who will eventually do groundbreaking work> will cause you to get a PhD, but the PhD may not be causally implicated.
We can see a good example of this in Judith Rich Harris, who was the sort of person to go to a PhD program, but was kicked out before she could finish, and yet went on to revolutionize developmental psychology anyways.
Also note that it was harder to get a PhD in the past. These days it’s easy enough that if you want to do research you might as well.
Not to be a jerk about it, but surely correlation doesn’t imply causation. A better explanation is that being <the sort of person who will eventually do groundbreaking work> will cause you to get a PhD, but the PhD may not be causally implicated.
We can see a good example of this in Judith Rich Harris, who was the sort of person to go to a PhD program, but was kicked out before she could finish, and yet went on to revolutionize developmental psychology anyways.
Also note that it was harder to get a PhD in the past. These days it’s easy enough that if you want to do research you might as well.