George Milling-Stanley, chief gold strategist at State Street Global Investment Management, believes bitcoin's recent surge may have given investors a false sense of security. "In simple terms, bitcoin is an investment looking for a return, which suggests investors are piling into bitcoin for capital gains, not because they see value or a use for it," says Mr. Milling-Stanley. The launch last week of options based on spot bitcoin ETFs, which allow investors to put in less cash to bet on bitcoin's price moves, rather than buying bitcoin itself, may have something to do with this.