One assumes that a math PhD went to the trouble of writing a dissertation so they could do something with it. I know little about the other fields you mentioned

One assumes that a math PhD went to the trouble of writing a dissertation so they could do something with it. I know little about the other fields you mentioned, but a PhD isn't needed for actuarial work. A bachelor's (heavy on the statistics) with some finance courses covers you, and after that it's self-study for the seven (7!) exams you need to be a fellow. A math PhD in an actuarial setting is out of place, like a CD grad working at Geek Squad (a hypothetical Geek Squad with pay comparable to programming).