I got very into it in the early days. Probably around 2007-2008, I was mapping parts of my large town in Australia. The data it had was pretty bad, with a lot of the roundabouts modelled as intersections and it didn’t have any new streets. Every week I rode my bike around parts of town capturing GPS trails to mark the streets. I would manually import the points and model the roads and carefully model the roundabouts (the tooling was very basic back then, roundabouts were hard to make).
Then one day I logged in and noticed ALL my edits were gone. The whole state had been mass updated in one go, with new street data that was donated by some agency. But it was so bad. It had roads marked that didn’t exist. Some new roads were marked but in the wrong place. And all the roundabouts were modelled as intersections again! I got so frustrated, I immediately logged off and I haven’t contributed to OSM since then.