Assuming the initial investment made to be around the 2012-13 mark, it was a pretty big gamble they took and it definitely paid off. From $120 to $12k is x100 in itself and with a $11 million investment back then, they have turned into billionaires! Wouldn't be surprised to hear more stories of early investors turning into billionaires by today as we're eyeing the $15k mark before 2018!
These Winklevoss brothers are one of the most popular investors in Bitcoin and I think there are more who remained anonymous or do not want any limelight focused on them as they are enjoying watching their Bitcoin soared into the sky and becoming billionaires too. It was indeed a big gamble for anyone to invest millions in those years when nobody can be sure what can happen with Bitcoin in the future. As proven by the twins, the gamble paid off big time because Bitcoin as the first and the original viable cryptocurrency made it to the moon. Aside from these Bitcoin billionaires, there are also many who became millionaires in the process as long as they never sold off their Bitcoin hoard when the price was already enticing. As the journey of Bitcoin continues, there would be more riches to be made although this time we really need a bigger capital if we plan to have a sizable Bitcoin holding.
I agree. I actually have my doubts on whether the twins are the first BTC billionaires (or half-billionaires). There could be other individuals that have just as much but have it spread across multiple addresses.