The Movie: David O. Selznick dreamed of adapting Margaret Mitchel's novel of Civil War romance for the big screen. So he did.
The Risk: Selznick spent $50,000 on the rights to the novel, and spared no expense getting it right. Casting alone took two years before Vivien Leigh (a star in Britain but unknown in the States) was confirmed as Scarlett O'Hara. And then it took a conveyor belt of three directors to call 'Action' on set.
Did It Pay Off?: All producers who think big point to this as their precedent - adjusted for inflation, no film has made as much money.