Winklevoss brothers invested $11 million when 1 bitcoin is amounted to around $120. An now it soared to over $10,000, that investment could be something.
They took a big risk at that time, and they had probably strong vision about botcoin future. At that time bitcoin was still at the begining and it has been great success for them, based on what I have read, they are not planning to sell their bitcoins as they see the growth potential - and they predict Bitcoin can surge at least 20x.