Once bitten twice shy. Once one has learned a lesson, one wants to prepare in advance to avoid the same pitfall.
When 2019 Novel Coronavirus started outside its country of origin, face masks ran out of stock. People wore face masks like it was in fashion. Hand sanitizers were snapped up by the dozens. Antiseptic alcohol was the next favorite sanitizer. In no time, all face masks disappeared from online sellers.
Online grocers struggled to fulfill orders.