Thomas Roukis would be another.
I don't have a perfect answer for you, but I'll throw this out there. In this profession we tend to view achievement transactionally. You did something. You got something for it. More money, Hospital employment. More letters. Better surgeon whatever. Everything in the end though is measured ultimately in money. That's not unreasonable since we all also tend up terribly in debt. Theoretically the PhD in and of itself should grow, challenge, teach, change you as a person while also allowing you to contribute to the literature, to the profession, to humanity, whatever. Yes, people have done these things without it. You should somehow be different than them. Whether you will be or what you will be - I can't say. Whether you will receive the transactional benefits - I don't know though again if you don't pursue them I think something went astray.
I actually see a cardiologist who has a PhD. I'll have to him why the next time I see him.