By going all-in, the major central banks are committing to a progressive increase in the complexity of global financial markets. As more individuals and pension funds abandon cash and safe-but-low-yielding paper for higher-yielding but more-volatile stocks and junk bonds, the system grows ever-more fragile, making a crash both likely and more destructive.
Another trait of complex systems is that the timing of their catastrophic failure is unpredictable. Once the conditions are in place the system can collapse immediately or continue on for a long time. Rickards’ analogy is a mountainside where snow accumulates until a single snowflake sets off an avalanche. But there’s no way to know which snowflake will be the one, or when it will fall.