It's not even true that COBOL programmers earn a lot of money because it's a niche and there are few programmers still writing it and banks are in a hurry to hire them. That's not my experience: all the COBOL programmers I know are mostly old guys earning average/below average salaries. And dealing with banks and similar institutions, which is a hell of its own.
If you like writing software and enjoy nice programming languages, COBOL is not for you. If you want to earn a lot of money or work on interesting projects, COBOL is not for you. If you're a bank manager, maybe COBOL is for you.