Ask HN: Is there a study that proves that older software is more expensive?

Im not sure how you would prove that

I worked on an old Java system for a few years. They have attempted to replace the system a few times - but each time these projects have failed at great expense, while maintaining the old system is costing a fraction of the cost of replacement

You also see this with the old cobol systems. One thing you find with cobol developers is that they roll their eyes at the next attempt to replace the system as they know it will ultimately fail. Thats why these systems are still around