The last time I experienced the grid going down for an extended period of time there was no way to spend with debit and credit cards either. Nobody accepts or spends gold as a currency, and cash and coin has been under assault for years.
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That's what I tell them, the grid goes down you fucked more ways than getting to your btc. Heck they use btc in Africa where the grid goes down constantly. The grid goes down where your bank is there is no way to get to it. Wit btc, you could do it with a cell signal, because it doesn't rely on one point.