I’d also note that COBOL is only one layer of the stack.

The real complexity lies in also understanding z/OS (mainframe operating systems), CICS, JCL, and the rest of the mainframe runtime, it’s an entirely parallel computing universe compared to the x86 space.

A lot of them are domestic, either in the public sector directly (so probably not really good money, but usually pretty decent benefits and job security) or with government contractors which require the work to be domestically (so maybe good money.)