I want to sell at the highest price, hold cash, and then buy it back when the price is lowest. This is the best operation, but it is often difficult. So once the price rises I will hold cash, and if the price falls I will buy it back.
That is nothing more than the standard strategy of a trader however selling at the very bottom of the price is incredibly difficult, selling close to the bottom is a lot easier, but selling your bitcoin for cash can be very troublesome, this is why many people decide to exchange their bitcoins for tether dollars instead, that way you get the convenience of using a cryptocurrency but with the stability of the dollar.