Billionaire Stanley Druckenmiller might not be a household name like Warren Buffett, but he's one of the best investors of all time.The George Soros protégé ran the Duquesne Capital Management hedge fund for nearly 30 years with an average annual return of 30% and no losing years. That's a phenomenal track record.These days, Druckenmiller is retired as a hedge fund manager since he closed his fund in 2010, but he still invests through the Duquesne Family Office, where he's made some smart buys in recent yea ...