This office views a high-risk business as any business that carries a high risk of massive liability. For example, a surgical practice, or a semi-truck delivery company bring to mind high potential risks. There's a greater chance that the surgeon or a semi-truck business is going to be involved in a fatality (or multiple fatalities) over the course of their careers. The damages from a single event could stretch into the tens of millions.
Businesses like these need more protections put into place to avoid losing everything if one of the high-risk events occurs. Sometimes the two company structure (see our real estate entity structures article) is not enough for such a business. Further, personal planning may be recommended in cases like a surgeon's because no entity will remove liability for your own personal negligence (the surgeon's malpractice exposure). Making both the practice AND your person look poor to a plaintiff's lawyer may be important in the case of the surgeon.