Why does the brain contain so much fat if fat isn't healthy?

Propaganda: Presume you are referring to dietary fat intake, and there are many fats that are critical to hormonal, endocrine, and immune functioning. Problem is mainly with trans fats and many saturated fats. For example, grass fed beef is far healthier than corn fed beef. This is far too complex herein, but a dietician can help clarify. (Also, weight loss can be facilitated by more dietary fat!)