Yes but that's why the market is not easy riches -- you don't know what the top and bottom will be until well after they happen.
For as many people here who understandably lament not taking some or more off the table when AVXL hit $14 (and there was only a very small time window to do that), I have come across just as many early investors in REGN, JAZZ, ACAD, etc, who lament the fact that they sold out at $60 and then the stock went up to $500.