Buying is most times the common action that everyone think is most appropriate whenever the market dips, however taking no action during a dip is relatively a form of action as well that may save you some unnecessary emotional tension. If i have invested a certain amount and set a duration for my investment to mature to an intended market price, i see no reason to take the action of buying more during a dip when i already have a target i'm working with. Dips provide opportunities for people to get into the market, sometimes it is not for you a hodler already to buy more, unless you didn't set any target and just interested in taking opportunity of the market.