It's a cycle so commonly we can probably expected it to happen. Without it, there could be an unbalanced in the system which is why things are simply go in cycle. Moreover, traders definitely would know and this is why we should be more patience and understand its behavior as it's unpredictable.
not unpredictable, because indeed we can only make predictions but the truth is we don't know. we usually make predictions based on trends from market movements, which are common. indeed nothing will definitely happen according to our predictions, but we try to make market analysis according to our ability to see the market. from there we can invest, not just speculating.