There's also a lot of people karma farming (for employment reasons?). A couple of years ago I was searching for something and the same question was asked by someone else on SO and this came up repeatedly while I was looking, but after 4 years there was no answer so it was a very low quality result. A couple of days later I did find/discover an answer so I went back to SO and added my reply, miraculously after 4 years someone else added an answer about 12 minutes later, it was the same answer as mine with a little more formatting and marked themselves as correct.

So after that experience would I go to the effort of contributing back again? Maybe in this case, because the answer was shorter than this post, but the equation might change if it required more effort.