I have never mourned on career changes. I do miss access to things associated with a former career. However, I can often buy or build what I need due to strong electromechanical skills developed along the way and or as side hustle skill builder type gigs taken oppertunistically.
Learning new things and working with others more skilled than I always pays off. I end up with the skill and have a pool of help available should I need it. I myself can help others too.
First change was from manufacturing as a prototype mechanic / planning production mfg engineer to pre-sales and training related to then high end CAD software and related systems engineering. (Sgi IRIX and Win NT) I could make almost anything I modeled.
Second change was from the CAD position to General management and engineering R&D at a small company needing some of both. This was fun. I got to use all accumulated skills. I picked up several more.
Third change was into the Additive Manufacturing industry as services lead, moving into product development.
Fourth and current is tech founder in an additive related startup about to be funded. This one also allows me to use all accumulated skills. Same industry, so this is more like a move, not change.
That is three real, leave old career behind type moves.
Times change, I tend to go where the opportunity is and will do what it takes to rapidly master new aspects while employing what I know and mentoring others, usually seeking to help make more of my type available. I have a few to my credit, all doing things in ways similar to my own path.
None of that was easy. Some of it was very difficult. All of it was fun and rewarding
The best thing I did along the way was to network, cultivate friendships and help others. When I need the same, I usually get it gladly.