now a lot of investors are investing in bitcoin, therefore bitcoin has increased very rapidly, if bitcoin decreased what should be done?, whether the investors will lose? 
law of supply and demand , if the bitcoin count will decrease the more it will be rare and rare over time . which means the price will go up,meaning more investors are buying and keeping it.
if there are many investors selling bitcoin it can be up or downs because of volatility and how bitcoin works for those big players,
you will not loose if you dont sell. technically it is the same as your money but if you do sell on low price you'll loose