But this is exactly the point - in countries where the local currency versus USD has had volatility comparable to BTC, it's been a big problem. E.g. in South Ko

But this is exactly the point - in countries where the local currency versus USD has had volatility comparable to BTC, it's been a big problem. E.g. in South Korea, where the volatility (and general upwards trend) in the Won last year was an order of magnitude less than BTC, the currency fluctuations have caused major losses and uncertainty for exporters. If you walk around Seoul, there are signs everywhere showing the current exchange rate.