When the nation’s currency falls, the balance sheets of local businesses — which have assets in rubles (or pesos or rupiah) but debts in dollars or euros — implode. This, in turn, inflicts severe damage on the domestic economy, undermining confidence and depressing the currency even more.
So what does this have to do with Putin? The answer is crony capitalism. Russia has been running trade surpluses (which should make the ruble appreciate), but this current account surplus has been offset with huge foreign borrowing by the private sector.
...walking around Mayfair in London, or (to a lesser extent) Manhattan’s Upper East Side, especially in the evening, and observing the long rows of luxury residences with no lights on — residences owned, as the line goes, by Chinese princelings, Middle Eastern sheikhs, and Russian oligarchs. Basically, Russia’s elite has been accumulating assets outside the country — luxury real estate is only the most visible example — and the flip side of that accumulation has been rising debt at home.