Panic buying only happens in the earliest stage of bitcoins just like at the stage of ethereum now, the price has been crashing and later you know it is back up again, that panic buying happen only during the time when the whales are taking care of to manipulate the price but now totally would not be possible.
Panic buying not only happen in the early stage. It happened when manipulators put up some nice scenarios that pushing the price up to a larger range. Because of that, it will make for a person/s to have a wild speculation that price will boost up more so there will be an increase of buying activities by those bullish persons.