That's because Cobol programmers probably make an order of magnitude greater income than on this chart. The only people who still write Cobol from my understanding are people who continuously update banking mainframe software. Government mainframes, etc. Usually these days you are apprenticed by someone with years of experience because of how difficult it is to obtain old documentation etc.
yeah that's why I mentioned it. Back in college, right before the year 2k, we had a special Cobol course they added just to get people some 2k jobs. I recall one guy who's still doing Cobol most of his time, working on old software like traffic lights systems (!)
A vocational school here in Sweden recently started offering a 1 year Cobol degree, ostensibly after demand from the banking and insurance sector.