As one who has posted a large number of projects on several sites let me add my two cents. I have been paid for some of these projects but most were done gratis. The money is trivial compared to the amount of work involved and in my opinion is not a motivating factor. Either you want to share and are willing to expend the effort to do so or not. What I see missing in the responses to this post is a discussion on the amount of work that is required to properly document a project, even a relatively simple project. Good photos and accurate drawings take time and some serious equipment. The single biggest impediment to me is the mickey mouse s/w used on these sights. Specifically the difficulty in incorporating photos and drawings. The software is far from intuitive and since my primary interest is in all things machine I do not want to spend a large amount of time learning or relearning the quirks of the software.
Currently I am working on a project that I have invested about 80 hours in and it will probably take another 40 or 50 to complete it. For every hour at the machine I spend an hour working on planning, drawings, documentation and photos. On several occasions I have pain painstakingly inputted the data only to find out that the finished product is not acceptable due to problems related to inserting photos and drawings. On several occasions the frustration level reached the point where I abandoned the effort and logged out. I have no doubt that these problems were a direct result of my ineptness at using the software, but then I am a simple hobbyist not a software engineer.
Responding to a post in most cases is pretty simple and straight forward because it just text. Adding the detail and editing is what takes time and the software at this site is about the same as other sites, arcane and not user friendly. I for one would be more amenable to posting more projects if the s/w were easier to use.
Just my two cents,
Jim