Get it to master the discipline

... not because a PhD will give you a living:

Openings for history faculty at the instructor and assistant professor level fell from 727 positions advertised in 2002–03 to 682 in 2003–04, the lowest point in the past five years. Most worrisome are the declines in fields with the most PhDs—North American and European history. Job openings in European history fell 18.5 percent from the year before, to 150 openings—the lowest level since the 1997–98 academic year. Openings for junior faculty in the history of North America decreased by 8.5 percent to 236 positions—again a five-year low.

And remember: there's always HAI.