I learned a lot in my PhD that I wouldn't have learned in my subsequent engineering job: Public speaking with confidence, how to be proactive in your job, how t

I learned a lot in my PhD that I wouldn't have learned in my subsequent engineering job: Public speaking with confidence, how to be proactive in your job, how to apply for public funding, teaching experience. How to present results, and how to write. I had exposure to what (at that time) were rare computing resources, which is useful now with in the cloud era. And I learned a ton about my specific field of course - which is probably not monetarily useful, but was a lot of fun and you can't learn it in such depth anywhere else.