Hidden Cobra and the worldwide ATM hacks
US-CERT on the August/September 2018 ATM hacks which affected several nations:
(...) all of the compromised switch application servers were running unsupported IBM Advanced Interactive eXecutive (AIX) operating system versions beyond the end of their service pack support dates;
This is the typical example of short-term thinking. Someone/some committee decides not to spend on a supported version of a particular software, but doesn't consider what the downside could be.