"But every hero has a fatal flaw. America's is its sharply increasing addiction to government debt. My calculations suggest it now takes nearly $2 of new government debt to generate an additional $1 of US GDP growth " a 50 per cent increase on just five years ago.

If any other country were spending this way, investors would be fleeing, but for now, they think America can get away with anything, as the world's leading economy and issuer of the reserve currency."

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