[steve_gh]

This is a very good answer!

I got a PhD almost 20 years ago (in ML). I worked hard and played hard - and had the time of my life. I learned to surf, got a black belt in Aikido, restored a sailboat, climbed 3 times a week, and made friends for life.

Professionally, it set me up to join industry, and put me on a technical fast track. Do I still use any of the research from my PhD - almost never (although I still dabble with NNs and GAs occasionally). Do I still use the overall research and organisational skills, and the critical thinking I learned - every day!

If you are a self-starter and have the right sort of intellectual curiosity, a PhD will be a worthwhile exercise, whatever you do afterwards. And, as the parent points out, the signalling that a PhD gives can be very useful. The fact that you completed a PhD points out that you are both smart, and can get things done.