They are advertising their game for free with this big Forum. Most of us know about his game from this very forum. He didn't get nothing from posting his product here for free. More people will know about the game, know who he is and will start to support him. It not just about the money, the support could come in many formsThat is true, and also at the same time false.
Many developers upload their own games here so that people can download for free, out of the goodness of their hearts.