Here are five of the motivation questions from my game modding survey (not a random sample), re-ordered and shown as a bar chart in percentages. Motivations about the industry in reddish tones on the left of each grouping, green in the middle is other players, and on the right of the groupings is fun and "improve the game for yourself". I know the colors aren't optimal but the chart does a good job of showing that people aren't motivated in relation to the industry. I don't think this says modders are selfish, I think this is a reflection of how people get an idea to improve a game (their own idea), and then make that idea via a mod since they want to improve the game based on their idea, and, it's fun.
Even zoomed out, you can see the pattern (but that could be a fabrication based on the questions, however, I did group the questions and the pattern is the end result, not the other way around). (The image/chart should really have a title, but it isn't meant to stand on its own. "Modder Motivations", perhaps.)
