There is a grain of truth in this accusation when levelled at the neoclassical school who only pay lip service to economic actors. However, even it recognises that equilibrium does not mean that the participants and their preferences, etc., have been isolated, only that their expectations and plans have been brought into consistency with each other. Soros finally reveals the source of his confusion and ignorance when he admits that his experience of money markets led him to his present views. Here he merely parrots the old cry that financial markets are inherently unstable, leading to breakdowns and depressions. It is this instability that led to the evolution of central banks.
Markets are basically stable.
What is not stable is monetary policy. And it is faulty monetary policies that destabilise economies. When the gold standard reigned supreme financial markets never witnessed the kind of prolonged financial gyrations that we are now experiencing. These wild fluctuations are basically caused by constant changes, and anticipated changes, in money supplies, price levels and exchange rates. Furthermore, nineteenth century depressions were caused by banks unofficially going off the gold standard by artificially lowering their interest rates through credit expansion.