I would bet that an extraordinary doctor can indeed touch millions. The best doctors reform the practices at their hospitals, improve the standard of care, and get brought in to do the same at other hospitals.
Programmers work in Medicine too. Specifically medical technology - things like Cat scans, MRIs, PET scans have probably saved many more lives than even the most extraordinary doctor.
Many of these devices were invented by doctors and implemented by programmers. The doctors, in many of these cases, were the ones who created most of the value.
When the idea behind a device is more like, "Here's how we're going to use magnets to align the polarization of water molecules in the body, measure those changes, and map those back to construct an accurate image of the inside of someone's body. Now program it for me.", the original inventor creates a whole lot more value than someone who says, "It's like Facebook for dogs. That uses PHP, right? Now program it for me."
