Price is the derivative of position changes - it reflects supply & demand in the market at that moment, which is often highest when everyone is entering the position.

When people are buying an asset speculatively, they often all enter the market at once, which drives up the price spectacularly. But then once they've all bought, what happens? That demand drops off; everyone who wants to own memory chip stocks already does. You're left with the value investors who already held and bought early, who see that their asset is now wildly overpriced and want to get rid of it. So the price then drops until that supply drops off and you reach a new equilibrium, often exacerbated by the speculators who see their position evaporate and want to get out.