I always thought what I wrote would last only months maybe a year or so; then 5 years passes, then 10. Some things I built which contain a lot of the first Delphi code I ever wrote (I was a Pascal coder before that) are still running production 30 years on. And that was the client saying we would probably rewrite ‘in a couple of years’.

Same goes for webcrap; I have some horrible php and jsp prototypes from the early 2000s which have been running production ever since.