I hesitate to recommend getting a PhD as a general recommendation for all researchers, but I will say that I learned so much during my own PhD that I would neve

I hesitate to recommend getting a PhD as a general recommendation for all researchers, but I will say that I learned so much during my own PhD that I would never have learned otherwise. One problem with self-directed learning is that you tend to focus on areas that interest you directly or immediately. Doing a PhD exposed me to many topics that I was completely unaware of and basically forced me to learn much more broadly than I would have otherwise done in a self-directed manner.