I am an ex-mathematician who went into industry, I would say apart from CompSci/ML and physics, it was one of the most sought-after PhDs you could have (across tech and finance) - when I was entering the job market 10 years ago at least. No regrets.
It's like engineers in post-Communist European countries, sure there were tons of graduates, but 80% of them were doing something else than the thing they graduated in.
But that's what everyone is lamenting the loss of, that AI is taking that specific job.
Going through forced detours in life doesn't make it a "good choice".
The good choices are the ones where people finish their studies/apprenticeships and then immediately work in their direct field. For example a law student becoming a lawyer.
At most I'd consider that a "mediocre choice".