On a much smaller scale, six years ago I inherited a service which previously had two people working on it full time. I've spent about a day a month on doing the bare minimum to keep it working ever since. Clearly we were massively overinvesting in it previously, right?

Recently it broke, and I have no clue how to get it working again. Fortunately it's just an internal thing so it's just disrupting work and not causing problems with customers, but now we're having to abruptly scramble to migrate off it and it's going to push back a lot of timelines. We got away with coasting on our upfront investment for six years, but it didn't last forever.