Only the public sector can create instability. •  second, that finance does not matter for real economy fluctuations. After the Real Business Cycles school, the rational expectations hypothesis and the intertemporal optimization paradigm, money and finance were considered not relevant anymore.
Later, in the new Keynesian consensual macro model money crept back in through the introduction of wage and price rigidities, allowing for short-term real economy effects of monetary policy. On the contrary, finance became invisible with the Efficient Market Hypothesis ensuring a reliable plumbing as servant of the real economy.