On January 1, 2000, the Y2K bug failed to end the world, because years of quiet work and hundreds of billions of dollars had already fixed it.
On this day in 2000, the calendar rolled from 99 to 00 and the lights stayed on. For most of the 1990s that outcome was far from certain. Older software stored the year as two digits to save memory, so a machine reading 00 could decide it was 1900 and act on it. Utilities, banks, airlines and hospitals all ran on code with that assumption buried inside.
What followed was one of the largest repair efforts ever attempted. Governments and companies spent years auditing systems, rewriting date handling and testing the fixes, at a cost estimated in the hundreds of billions of dollars. Households stocked water, cash and canned goods in case the work fell short. When midnight came, the failures were small and scattered, and the world went back to work on Monday.
Y2K is remembered as a scare because the fix worked, and that is the part worth keeping. Preparation that succeeds always looks like an overreaction afterward, which is exactly why it gets abandoned. The cash, water and food sitting unused in January 2000 were never wasted, because the same shelf turns an extended power outage into an inconvenience, and most man made disasters arrive without the courtesy of a countdown.