The last plumber I had any dealings with was a nice guy in NYC who collected antique cars and drove around in a vintage Corvette to and from work. He handled mainly industrial accounts and did first rate work earning him a reputation for fairness and good work. He had to turn away business. And yes, he made well over $200,000. He also employed numerous people whom he trained to get their plumber's licenses.
We relied on him for our regular maintenance and knew that in an emergency he or a trained substitute would be there within an hour. We paid a little more for the service and never regretted it.