Personally, when I cite a wikipedia article it’s usually one that covers something I already know about, so I can look at it and confirm that it’s right. In those cases, I could probably write the same stuff myself, but why bother when someone else has already done it. And their version has the advantage of being proofread and expanded by other people.
And anyway, I don’t think the stuff on wikipedia is really any more suspect than most of the stuff on the Internet, news articles included. It’s generally been proofread by more people than most Internet content. Of course, if you can cite a publication by a known expert in the field, that’s certainly more authoritative. But often those kind of sources aren’t easy to find on the Internet, and if you cite a book it’s a lot more trouble for people to go look it up.
I do it because I think it’s a really cool idea. Plus it’s a lot of fun and it’s possibly the only online community with MORE smart people than the SDMB (and fewer pit trolls, too).
I have somewhere between 6000 and 7000 edits; I’m an administrator and an Arbitrator. I could safely be said to be a major contributor, even if I rarely actually edit articles anymore.
I’ve added myself to the Teeming Millions list in Wikipedia space. Hopefully some loser won’t get the idea to delete it the way the Advogato cross-reference list was…
I dabble a bit in Wikipedia, occasionally translating Spanish Wikipedia articles to English (where the Spanish article is more complete than the English one). I also write the occasional stub.
Why? Partly for the fame of seeing people read something I wrote, partly to keep my Spanish in shape, and partly because I think people contributing to a common base of knowledge is a very good thing.
Mostly to contribute some obscure fact or snippet. I contributed the small article about Italian Baroque guitarist and composer Count Lodovico Roncalli.
I’ve added some things to articles about early Beatles members Pete Best and Stuart Sutcliffe, but the article on the former has been completely rewritten since then.
I added some comments to the German Language article saying that the much bally-hooed grammatical complexity was a bit exaggerated, and to the same article I added some words to the list of English/German cognates.
I’d go along with most of what’s been written here already. It’s fun - even a little addictive - to contribute some your own knowledge, to polish what’s already been written by others, to expand an entry that is otherwise too skimpy, etc. You’re doing your part to enlarge the store of human knowledge in its most current and accessible form. What’s not to like?
I also enjoy going back a week or a month later to see if what I wrote is still there. More often than not, it is, sometimes verbatim. Then I like giving my own work a polish to make it even better.