During the next major decline the average investor will realize the investment products they have been sold (mutual funds and ETFs) do not have ample liquidity behind them. When this realization sinks in it will only feed the panic and investors will rush to sell more in an environment where there are no bids on the buying side. High frequency traders will step away, as they always do, creating massive flash crashes on the way down. Have we started that process? I have no idea, but it's coming. Stability breeds instability and we have had a fairy tale financial environment for 7 long years. We are due for an avalanche.
For more see: Tranquility Creates Fragility: The Coming Collapse Of Financial Markets