Actually bitcoin is like others coin so its price can be high and low. So if people see that the price of bitcoin is high so they can sell. They can save something for the future also. There is nothing as stupid decision.
Nobody can't dictate somebody on what to do with his bitcoin. That is decentralization, nobody is in control. Even if the price of bitcoin is low and in real life he just needed some money for emergency then bitcoin could be his savior. That is not a stupid decision and i even think that it is wise to do so.