TOKYO — Anyone who thinks gold’s surge into the stratosphere represents irrational exuberance isn’t paying attention to the wretched state of the Group of Seven (G7) economies. US government debt is topping US$37 trillion, giving ratings agencies cause to reassess the world’s largest economy’s underlying health. France’s dueling political and debt crises have the International Monetary Fund gauging its available reserves. Germany is skirting recession, with industrial output plunging 4.3% in August from July. Over in London, some commentators wonder how long the UK can avoid a 1970s-style date with the...