That sloppy piece of code you wrote today could well be used by someone in 50 years, so maybe you should think twice about the sloppiness.
That's my take on Tim Bray's observation that each year over 5 Billion lines of COBOL gets written and added to the 200 Billion lines of code in production.
Reimplementation is a very costly affair - and it's not just the cost. It's risky too.

We've been told for ages that COBOL was dead. Few schools teach it. Nobody learns about it until they get hired into a team that still uses it. In 1999 we were told about the armies of retired COBOL-slingers that got hired back for one last shoot-out at the Y2K Corral because there weren't any active developers to take on the job.
But if the figure of 5 Billion lines is right, then we might try some math. Let's assume an average developer can produce 100 lines of code per day and works 250 days a year (COBOL developers just don't DO holidays - they're too mission critical) then we arrive at a figure of 200000 active COBOL developers. Since I think we were flattering the COBOL developers with both the 100 and the 250 it could easily be a million instead.
That's maybe not as many as there are Java developers but is not exactly a population size that one would consider threatened by extinction.