What does Y2K have to do with the world ending?

Answer 1

Many believed in the year preceding 2000 CE that computers, many of which base their dating system using the last two digits of the year making 1999 = 99 and 2000 = 00 for example, would then equate the year 2000 to the year 1900 (because the final two digits are identical) and believe that they should not have been invented, thus resulting in their failure.

Despite the obvious stupidity involved - computers lack the intelligence to decide whether or not they should exist - this grew to the extent that people feared the systems keeping nuclear weapons would be activated or conversely that the safety features would fail, resulting in nuclear winter and the end of the world as we know it.

Equally obviously, this did not occur.