Why you should temporarily ignore the "1000 True Fans" concept—if you want to get ahead

The 1000 true fans concept seems to follow a simple multiplication rule. If you have a thousand fans and they buy $100 worth of product in a year, you earn $100,000. Which sounds perfectly fine when you're doing the multiplication, but falls apart in reality? Where are the flaws in the 1000 fans concept? And what if we went down from 1000 to just one? Just one? As in "zero to one"? Let's find out.