Coinbase (NASDAQ:COIN) CEO Brian Armstrong has made a prediction about the future of cryptocurrencies like Bitcoin (CRYPTO: BTC) and Ethereum (CRYPTO: ETH), stating that if the current growth rate persists, there could be two to three billion people using crypto within a decade. What Happened: Armstrong, on Monday, retweeted a thread from Goldfinch CEO Blake West, who expressed frustration with people who dismiss cryptocurrencies as useless.