Study highlights growing significance of cryptocurrencies   More than 3 million people (three times previous estimates) are estimated to be actively using cryptocurrencies like bitcoin, finds the first global cryptocurrency benchmarking study by the Cambridge Centre for Alternative Finance. While many members of the general public may have heard of "bitcoin", the first decentralised cryptocurrency launched in 2009, a new report from the Cambridge Centre for Alternative Finance (CCAF) paints a broader picture of "cryptocurrencies". The report shows that cryptocurrencies…