This topic comes up from time to time. The last in-depth discussion was about two months ago. The short answer is that most of the flairs and moderators here don't contribute, or at least don't contribute any more (count me among one of them) because of Wikipedia's policies. In the early years of the site, it was easy to contribute, and getting your answers to stick didn't require arcane knowledge of obscure policies. Anymore, making a change is a journey into bureaucracy rather than knowledge.

I believe /u/restricteddata said it best:

The way you "win" at editing a Wikipedia article is to master their rules (usually the deep ins and outs of WP:NPOV, which is a convoluted "cascade" of dubious epistemological distinctions* that can allow just about any perspective to get a foothold in an article, mixed with the rules on how disputes are supposed to be handled), and patiently, over a very long period of time, use them to your advantage. That is it. It has nothing to do with factual anything. It has to do with rule mastery mixed with a game of endurance — whomever is willing to argue and arbitrate the longest usually wins.

The bottom line is that it isn't worth the time you have to put into it.

I do, but not on history-based articles. I largely focus on hockey-related things, and even then I've had to limit my time recently due to other commitments. I do take pride in the quality of the hockey articles there, which I'd argue are up to a decently high standard and some of the best sources on some topics anywhere, if I may brag a bit.

I went about the task of editing an article one time. It convinced me of the error of my ways. Also, I have gone back since and it has been changed back to the (innacurate) original

I have written about a dozen articles for Wikipedia, and try to add more from time to time. I don't touch any of the articles on well established figures or ideas, because (as others here have mentioned) they tend to devolve into shouting matches. Instead, I try and add citations or correct misquotations in smaller articles to try and make the website more reliable.

I normally write biographical entries for people who either don't have their own page, or expand on biographical stubs for people that deserve more than 6 words (e.g. William Cosyn)