When you buy at a high price and because the market falls you panic and sell low, and by selling low you will lose. If there is a decline in the market, holding is the best choice to save from losses, but the decision is yours, choose the best for yourself.
yes holding the coins will help in getting back huge profit when the market is up and bump again. There are few hard times we have seen for BTC and again it recovered with positive results so waiting with patience is the key to success in the crypt market.