Just a trivia question, but are there any persons who hold US$1,000,000,000 in bitcoin yet? According to CoinDesk[0], the total value of all bitcoin has just passed $40,000,000,000. So it's certainly possible. At the current value of bitcoin (2,546.85) that's a mere Ƀ392,641.89.
[0] http://www.coindesk.com/data/bitcoin-market-capitalization/