Big volume kills moves. Climax blow-offs take both buyers and sellers out of the market and lead to sideways action. Trends never turn on a dime. Reversals build slowly. The first sharp dip always finds buyers and the first sharp rise always finds sellers.
Bottoms take longer to form than tops.
Greed acts more quickly than fear and causes stocks to drop from their own weight. Beat the crowd in and out the door. You have to take their money before they take yours, period. Reversals at the first test of a new high or low are common. Investors jump out at double tops after missing the first exit while value players buy double bottoms.