[brudgers]

A Phd takes n years. A person could spend n years figuring out what they wanted to do without getting a Phd. The OP has spent n years figuring it out and has a Phd. Plus the habits and skills necessary to earn a Phd that are independent of domain knowledge. Few people have what that takes.

[mister_hn]

Sure, but to earn a PhD you have also to submit and present an amount of publications and even after that, to make the title relevant, you should continue with the subject and the activities.

[aqui_c]

It depends on whether you judge degrees from a purely utilitaristic view, plus PhD is closer to working than studying. If you work 10 years in a company, and then you write a book, would you wonder what are you doing with the title you earned at your job?

[brudgers]

you should

Nobody should unless they choose to. Not me, not the OP, or even “you”. The title is clear.