Some years ago I remember somebody (maybe Tim Bray) had a post that the people who had the best careers in Tech would go to secure government positions during recessions, where they would generally work on crafting the standards other people would have to follow, after the recession they would move into a period of private consulting on the standards they had just designed. I think the PhD argument is a variant of that.

It is of course correct that if you are so good at predicting recessions that you could use this strategy effectively then probably your best monetizing possibility would be just predicting recessions and investing based on that. But then it is not sure that people will do the most effective thing either.