The apprehension people had at the end of the 1990s. There were several reasons. Just the utterance of the year "two thousand" sounded so strange that people were afraid. For a hundred years, all time was focused on life in the 1900s, 1920s, 1930s, etc. By the 1990s, very few people were even alive before 1900.
In the 1980s, the personal computer industry exploded, bringing a somewhat foreign technology for people right into their living rooms. For many, especially the elderly, there was plenty of high-tech anxiety in the 1990s. See
Y2K fashion and
Y2K problem.
Doomed When the Clock Strikes Midnight
Because a year was stored as two digits in millions of databases, there was plenty of apprehension about the date changing from 1999 to 2000. However, that anxiety was not well founded because hundreds of billions of dollars were spent to upgrade computers worldwide, and very few data errors occurred as a result. MVS was the major IBM mainframe operating system at the time (see
MVS).