George Milling-Stanley, chief gold strategist at State Street Global Advisors, believes bitcoin's recent surge may be giving investors a false sense of security. "In simple terms, bitcoin is an investment seeking a return, which suggests investors are piling into bitcoin for capital gains, not because they see value or 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, may have something to do with this.