I don’t understand how he can run an office without a staff.
An office needs someone at the front desk, assistants to help room patients, check vitals, address medical issues over the phone (e.g. “I have a low grade fever, should I make an appointment to come in?”), manage prescription refills etc. He needs someone to send/receive medical records, referrals, order supplies, schedule equipment/facility repairs/upkeep, oversee the bookkeeping, marketing/website, manage the IT/electronic health records system, maintain credentialing, maintain memberships in the various professional organizations, coordinate legal issues, manage the various insurances for the practice (business liability, malpractice, etc.), oversee that regulations are being maintained, such as emergency plans for fire evacuation routes, gas leaks, etc.
I do a lot of this stuff in my daily job, and it’s just the tip of the iceberg. Excluding insurance will save some overhead (we have 1.5 employees who deal with scheduling, billing, insurance prior authorization, appeals, etc.). That’s just a small chunk of the overall care team we have though. I can’t imagine how one person could handle all of that, AND see patients all day, keep current on healthcare advances, and all of the other duties a physician has to keep up with.