KITCO NEWS - The cryptocurrency craze continues with the leading virtual currency - Bitcoin - trading near record highs. But, to bestselling author and currency expert Jim Rickards, the new age currency may be in a bubble. Delving into the theory of valuation, the Currency Wars author said that even if investors seem to be expressing a liquidity preference for Bitcoin over the dollar, it doesn't necessarily mean they are losing confidence in the greenback. 'If you were losing confidence in the dollar than gold would be going up and it's not, so it looks like a bubble,' he told Kitco News. He added that investors should not worry that virtual currencies take over the U.S. dollar's reserve currency status any time soon because the market is just too small. Another facet that investors may be ignoring, Rickards continued, is that investors racking up substantial gains from crypto investments might not be properly filing their taxes. "The IRS could subpoena one of these [cryptocurrency] exchanges and freeze up all the bitcoin,' he said. 'The IRS did this with Americans with Swiss bank accounts, they'll do it with bitcoin.'