I wanted to see what the COBOL job market looked like. So I learned the superficial basics of COBOL in a day or two, just so I wouldn't be a complete fraud when I put it into my linkedin profile as a skill to see what happens.
Yeah I think that's mostly a myth. When I looked up salaries they were definitely good (for programming; amazing for the average person), but not "I would write COBOL for that" good.
There aren't really that many old COBOL systems around. I think it's mostly just over-reported because you can write an article about how some government department still uses COBOL but you can't write about one that switched to Java.