Given the chance, I'd do PhD in math for the sole purpose of learning how to think straight and see the projects through start to end on my own. That's what PhD means to me anyway.

PhDs need to be banned. It is basically bunch of professors who exploit a bunch of graduate students from foreign countries. The professors controls the visa which effectively controls the student. The worst offenders are usually the Foreign professors which is ironic since they should be the ones to realize how harmful it is. A professors tried pull this stunt on me, but he didn't realize I had papers. So got the hell away from his lab.

Obviously, current vogue is for AI / ML / CV expertise. With compensation of $1M right out of school not unheard of.

Personally, if I chose to go the academic route. I'd like to have a lab at an institution such as the Broad Institute. Systems biology at the frontier of human understanding.

https://www.broadinstitute.org/

If I had the necessary schooling up front, I would go for anything related to bioengineering. It seems like the most interesting and high-impact field currently out there (next to AI, although I think in bioengineering you might have a more direct impact sooner).

Is it still worth it to do a PhD? Just wondering...

Mathematics