Do some doctors regret becoming doctors? Why? How common is this?

 I once went out for a lunch buffet with an Indian doctor in Tennessee. I went to discuss some business related to practice management software. As we began to have our lunch, an young intern of his joined us. It was a big buffet. So, we had time to talk.We discussed his practice, about ICD-9 to ICD-10 transition and his general state of affairs. He had been in business for more than a decade. So, he was quite well set. Coming from India, he talked about how he came to pursue this line of occupation rather than the Engineering line. It was not surprising considering that most of the Indians growing in the 80s and 90s mostly had the doctor (MBBS) or engineer (BTech) educations to choose from.However, as we began to talk about the money part of his business, I sensed that things were not going that well as he would have wanted or as much as he had expected when he chose this profession. It was not because he was losing customers or that there was competition. He talked about how the health insurance industry was making it hard for him to get paid. You see in the US, the healthcare insurance companies get into the act once a patient visits a doctor. They go through the due diligence procedures (Coding, billing, claims and whole 9 yards) before the doctors and hospitals would get paid. The doctor talked about how delayed payments were upsetting his small practice. He grumbled about how it was no longer lucrative to be in this line of occupation. What’s more, he wouldn’t encourage his own children to purse it. I was surprised that he was that frank about it in front of his intern.I think the hard times were speaking, but what really amazed me was what the doctor did next at the lunch table. As the waiter placed one more plate of the Indian Naan on the table, the doctor quickly covered it in the paper napkin and swiftly / secretly pushed it in his suitcase.I was sad to see that happen, but more sorry to see him do it in front of his intern.As I drove home after the lunch, I thought it was not this particular doctor’s problem. It could more likely be the problem with the US industry as a whole which must have forced him to regret his career choice.

Edit 1: After posting my answer and seeing some of the comments here, I think I need to explain a few things:

1. The doctor clearly mentioned the problem with insurance regulations and how they were impacting his practice. That was the crux of his situation. It had nothing to do with his own personal motivation(s) to stay put or get out of this line of occupation. I have seen other answers where they have talked about how the industry is getting stifled by regulations which are beyond the control of a small practice.
2. When I said “lucrative”, I did not mean to say “huge amount of money” or “insanely large amounts of profit”. There is no implication of “greed”. The point is that when you take up a career, you research how stable you will be in that line. When you study to be a doctor, the general thinking is that you are going to be reasonably well-off. I think, in comparison with other career choices, a doctor’s earnings should be fairly good enough for parents to send their children to a medical school.
3. The example I gave of the naan could well be wrong. I could have been wrong in connecting the doctor’s frustrations with pushing the naan into his suitcase. And hey, who is to say if the doctor just liked a naan to take home. And what’s more (and everyone knows), how awesomely tasty naans are.