The tech being obsolete is why Y2K was a smaller problem than it would have been otherwise. Most places were no longer running much COBOL code. But banks are famously slow to upgrade their tech, and for good reason much of the time, so most of the world's remaining COBOL code (and other code too, COBOL is just what I'm most familiar with, not that I'm all that familiar with it) was in banks and other financial institutions.