The specific problem with COBOL is that COBOL is both a language that was badly designed on the day it was created and that there is a stigma against programmers who have worked with it. This stigma is also a problem for other languages such as Visual Basic and PHP and it can make it harder to find programmers willing to work in those languages. Nobody wants to be "unemployable" because they worked in a stigmatized programming language even though the idea of stigmatizing programming languages is objectively idiotic.

This wouldn't be a problem if organizations that are still using COBOL code would pay high salaries for COBOL programmers because there are people who are only writing code for the money who'd be happy to work with a terrible programming language if it makes them money. But they generally also want to pay antiquated salaries from decades ago for COBOL jobs if they even offer a salary at all. Because they would have migrated their system off of COBOL decades ago if they actually cared about properly maintaining it!