A friend of mine went from attorney to private chef. But she worked in the industry for a couple of years in catering before taking a job as a private chef. In her case, she needed catering experience since the family entertained. She also had to be flexible enough to travel for long periods as the family owned and used several homes, some times staying at a second home for couple of months at a time. I will mention that after 3 years, she just resigned. She reinstated her law license, but still isn't sure if she wants to go back to the grind of practicing law.
Another acquaintance works part-time as a private chef, then teaches the rest of the time. The family that employs him has him come in several times a week to prepare meals; some of which are served that day; some prepared and stored for later in the week. The family is Indian, so the wife actually taught him how to prepare her family's favorite recipes. He shared several recipes with me and they are excellent.
As a general rule, most people want to hire someone with training, experience and knowledge of both classic and current trends. As the experiences of the two chefs I know who work as private chefs shows, the requirements and demands will vary greatly by clients.