All aboard the billionaires' Bitcoin bandwagon? Mark Gilbert and Lionel Laurent, Bloomberg News A new rush. , Photographer: Chris Ratcliffe/Bloomberg (Bloomberg Opinion) -- Now that Bitcoin has topped US$20,000 for the first time, should you shift your hard-earned cash into digital currencies? History suggests caution should be your watchword, no matter how strong the fear of missing out may be. News on Wednesday that One River Asset Management has set up a fund company that will have about US$1 billion in Bitcoin and fellow digital coin Ether by early next year suggests that institutional investors are starting to take cryptocurrencies more seriously.