This is not at a size where it’s a macroeconomic risk to the global economy, but when prices are moving like that, my view would be investors need to do their homework. This is not a currency in the accepted sense. There’s no central bank that stands behind it. For me, it’s much more like a commodity.
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Bitcoin Not Threat to Global Economy, Says Bank of England.
Bitcoin is not just a currency but also offers opportunities for the speculative gains and hence it won't cause any direct damage to the banking system. However, indirectly the consequences of growth as a payment system, it might reduce the flow of revenue of the banks. If it is emerging as a stable technology to transfer the funds at low cost then naturally it will reduce the dependability on the whole banking system.