The Tesla situation is really fascinating from both a microeconomic and macroeconomic standpoint. Generally, the assumption in most economic analysis is that purchase/sales decisions are based on factors mostly intrinsic to the brand and item. Celebrity endorsements can change those curves somewhat -- sometimes significantly improving them. But it is rare (in my experience, anyway) to see a precipitous decline in a major item (like a car or truck) that is almost entirely tied to the perceived personality and personal actions of a CEO. I can't offhand think of any other examples that approximate this situation.