I mean, losing money is not sustainable. If a doctor or physician group isn't business savvy and can't earn a profit they will eventually go under. That's not good for the patient.
Simple example pitch that many general practitioners might consider using (based on local laws, of course):
“Insurance covers C, Y, and Z. I can offer these additional services for A, B, and C that are not covered by insurance.”
Where I live, you get a lot of this via “concierge doctors”, but that system can go far beyond basic concierge service, and people are willing to pay for top quality care.