The market is a pendulum that forever swings between unsustainable optimism (which makes stocks too expensive) and unjustified pessimism (which makes them too cheap). The intelligent investor is a realist who sells to optimists and buys from pessimists.
And when they leave,they take your life of details with them. You are expected to move on again, but you don't remember what it was that moved you, because no one's asked you in so long. Not even yourself.