The problem with Y2K was the fact that very few computer systems were coded to accommodate a date past Dec 31, 1999. If putting in January 1, 2000 the greatest scare was, the computer systems would simply not respond (or crash).
I was working in IT at that time also, computer engineers and every business that depended on computer technology were very, very much aware of the disastrous potential of the date problem.
As NY_Dutch said above, a LOT of work went into computer coding to correct the date. The development and the upgrading of every system, from a local bank to a gas station to the computer banks at the Pentagon were corrected to overcome. And the end of the world did not happen.