I've tried using it over the years but I never liked it because there was no information. So last night I looked at my local city and there is almost no information at all. I spent a few hours last night adding buildings and restaurants and removing incorrect items. It was actually kind of fun and therapeutic and I plan to do more of it tonight. My girlfriend thinks it's dumb and I'm wasting my time because Google maps and Apple maps and Bing maps exists but she just doesn't understand open source.
Edit: Apologies, I just realized this question is not Linux specific.
I contribute as much as I can, mostly through StreetComplete. I see it as a hobby when it isn't too hot/cold outside, to take a walk around my area and map houses and addresses. I find it super important
I second StreetComplete. I actually had quite a surprise when I first installed it - I expected to have a lot of mapping work ahead of me in my somewhat rural area, but most of it had been mapped in a lot of detail already.