Avoiding the double effort of academic research and marketable job skills as a math PhD
A math PhD will teach you a large number of completely marketable, industry-ready skills:

how to think logically and analytically

how to research challenging technical topics on your own, solve problems, and pursue difficult goals over an extended period of time, overcoming frustration and maintaining a good level of motivation

how to communicate your ideas effectively, in writing and in person (in particular, if you gain teaching experience while doing your PhD your presentation skills will end up orders of magnitude better than those of your peers who went into industry straight out of college)

and many other “soft” skills that are difficult to quantify and describe but are nonetheless extremely useful and important.


All of these things add up to a very attractive package for employers. It’s easy to focus on the “esoteric math” part of a PhD and conclude that it’s a “waste”. Will an industry job give you an opportunity to use your knowledge of Schur’s lemma or Brouwer’s fixed point theorem, or show off your familiarity with Radon-Nikodym derivatives? Probably not. But that doesn’t mean you will have wasted your efforts learning those things. Along the way, you will have learned to look at the world like a mathematician, and that, as it happens, is a darn useful skill almost anywhere you go.