I often see panic selling, but panic buy i don't really know about it.
Perhaps it's rarely happen, not just like the panic selling cause people get afraid of getting lost on their investment.
therefore the best is that the buyer panics from the panicked seller, because the panicked seller will definitely suffer losses and losses from the panicked buyer because the price of the coin rises before he buys
Maybe when bitcoin get its ATH, many people do panic buy because they see bitcoin will to the moon and they bought btc in high price. When bitcoin down they get loses their money.