What I've learned, from raising three kids, is the more you give them, the more they come to expect. Adult children have an obligation to help defray the cost of their living at home. Whether the parents need the money or not should have no influence on the decision. Children need to learn responsibility and the cost of being independent, something they eventually will have to become. And if they keep acting like kids, push them out of the nest. They might not like it then, but they will appreciate it later because they will grow up sooner.
“Travel is fatal to prejudice, bigotry, and narrow-mindedness..." - Mark Twain