I have a 10 year old Giant Terrago (the V brakes one) that still has the original drivechain on it and it works fine (although I know it’ll now explode the next time I look at it 🙄 ).
I bought the bike new and used it at least weekly for the first 3 years of its life and I’ve ridden the coats to coast on it 3 times.
It’s been my pub/hack bike for the past 4 years with 2/3 ride a week.
I’ve got to the point with it that I know the entire drivechain will need to be replaced en-masse (I’ve even got the parts ready) but as it only gets used for short runs of <2 miles I’m not going to be too far from home if when it breaks so I’m just going to see how long it will actually last 😀
It still shifts fine btw