How to understand this sentence?

If you are not a good doctor, you are a good doctor.

Good looks and good doctors are all expectations and longings. If you have great talent, you should be a prime minister and save the people in from the mire. If not, you should treat patients and save lives. No matter what resources, they are dedicated to the people.

In fact, this is an allusion:

Fan Zhongyan of the Song Dynasty knew his ambition from an early age. Once he happened to go to a fortune teller and saw a fortune teller. He simply asked the fortune teller, "Please take a look at it for me. Can I be the prime minister?" This fortune teller may have never seen it in his life, and a child was shocked to say that he wanted to be a prime minister. Tell Fan Zhongyan, "Why are you so eloquent at an early age? Later, Fan Zhongyan was a little embarrassed and said to him, "Do you think I can be a doctor?" The fortune teller was puzzled and asked him, "Why did you choose these two volunteers? Fan Zhongyan replied: "Because only a good doctor can save people." After hearing this, the fortune teller was very moved. A child was bent on saving lives, so the fortune teller immediately said to Fan Zhongyan, "You have this heart. This is called the real heart of the prime minister, and you will definitely be the prime minister in the future." -Excerpted from Teacher Cai Lixu's Lecture on Happy Life-How to Be a Real Good Man.