It sounds like the OP is asking "is a PhD a good way for me to actually accomplish something in my hobby area?" In which case the answer is no. A PhD is a way

It sounds like the OP is asking "is a PhD a good way for me to actually accomplish something in my hobby area?" In which case the answer is no. A PhD is a way to obsess about a highly particular part of some field to the point that you can finally gain entry to academia where you can continue to obsess about particulars while balancing teaching students for the rest of your career. If that's what you want, more power to you, the world is a better one because of people like that, but that doesn't sounds like where you want to go.