The studies that show [the economic benefit of an advanced degree] typically crunch broad swaths of data. They look at the census, or other large population samples, and show a positive correlation between income and years of education. This means that college and graduate school are generally a good bet. But it doesn't tell you that every single degree pays off financially at every single point in time.And so there are lots of just-graduated grad students, many with debt from student loans, unable to do the work they're highly qualified to do.
I'm fortunate in multiple regards, here; I've probably got another two years to go, thanks to a just-received DDIG, so I'm not hitting the job market until the worst has (hopefully) passed. Because I've been lucky enough to be funded as either a teaching assistant or a research assistant (and can expect continued funding as one or the other), I don't have new debt related to grad school, even if I'm not exactly getting rich doing it. Being in a mostly NSF-funded field has been harrowing in recent years, but under the new administration things are looking better for funding in pure science - NSF did pretty well under the stimulus package, and should see better treatment in the regular budget, too. My only major worry is that when I graduate, I'll be competing for post-doctoral spots with an extra-large cohort of other folks who waited out the downturn as students.