the peak, we have inflated expectations and people think price will never stop rising. Then we crash and most people become disillusioned. Then we return to the mean and wait -- almost in dormancy -- until the next run gets triggered.
That's why experts says SELL when others are greedy and BUY others are fearful. Also, you need to adjust your investment strategy according to market condition. Not many can be exact true about top of high and bottom of the low, some may buy or sell into that exact point by chance and by expertise but otherwise all others cannot figure out the exact top or bottom.