The problem w Bitcoin as a global reserve currency is that it cannot be manipulated by the nation-state. Manipulation in this case is not a bad thing it is actually a safety feature for society against pure supply/demand dynamics. The prevailing wisdom is that having a fiat currency which value and velocity can be manipulated by, granted the Fed Reserve is a quasi govt agency, in times of emergency helps preserve the social order and smooth fluctuations. So Bitcoin has no value as a reserve currency unless it could be manipulated by the state, which it can’t, so it won’t.