Look: all you millennials making fun of us old farts for making a big deal out of the Y2K "bug" (not a bug but a crisis actually) you weren't there working in the trenches, you don't know shit about it, and so you should listen to us old farts instead of trying to take the piss out of us for what you think was scaremongering. This was a HUGE problem - especially when we're talking about embedded systems. I spent five years on-and-off testing and remeditating systems in anticipation of the date roll-over. There were countless systems that would have fundamentally failed if not fixed. And while I can't speak to the issues faced in many other specialties, some examples I personally worked on included : a) a number of widely-deployed medical dosimetric pump models that would have just silently stopped working on Jan. 1, b) some large-ship engine maintenance controllers that would not have issued maintenance alerts because their internal date calculations erroneously indicated no maintenance was due for decades and some that could no longer calculate fuel level (due to consumption-over-time calc issues), c) most legacy accounting software suites couldn't properly calculate payable and receivable aging, d) banking systems that would suddenly calculate a hundred years of interest on a balance, and e) payroll systems that would have deducted a year's worth of benefits and tax in the first payroll of the year 2K. There were numerous other similar issues – many of which were difficult to even FIND because the machines were tucked away in a closet in some factory or nuclear power plant basement that no one had even looked at in years because, well fuck, they always just worked. You need to understand that in many cases we were dealing with arcane, very poorly-documented and understood systems.
But the point is that millions of techs spent many millions of hours to FIX THE SHIT . BILLIONS and BILLIONS of dollars were spent world-wide on Y2K remediation over just a few years. I made a shit-ton of money doing that – and bear “workplace politic scars” as a result because of pin-head non-tech managers who just didn't get it. And I worked alongside other firms that had dozens and dozens of coders and engineers whose SOLE JOB for years was Y2K remediation of legacy systems. Generally, we're not talking about systems designed and implemented in the 90's but systems that originated in the 70's and 80's that had basically still ran the world in the 90's! This is code running on a host of even-then obsolete Z80 and 8080-based industrial microcontrollers and also computers made in the 70's and 80's by the likes of DEC, MAI, Tandem, Altos, IBM, Wang, Ohio Scientific, etc. running COBOL, FORTRAN, MAI BASIC, VAX BASIC, DEC BASIC, FoxPRO (er, foxbasic) and tons of other languages (damn, coders these days have no fucking idea how much of world commerce was controlled by the BASIC language in all it's multifarious forms!). And I worked on all those and more. Much of the code we fixed for the Y2K bug was trivial, and some of it was important. Many technical papers I read at the time indicated there were many systems out there that were really critical to fix - though I didn't work on many such, I know people who did and it was scary.
So yeah, the world wouldn't have ended but we would all have lived with a lot of pain for a while if so many talented people hadn't realised there was a problem and worked so fucking hard to fix the shit that we inherited. If you weren't in the trenches then you really have no idea about how bad it could have been if not for all the talented people heeding the alarms that started ringing in the mid 90's.