What’s wrong with saying, “I’m your mother and because I love you I will not do anything to help you after college so grow up, or you will be homeless. Because kids are smarter than you think to buy that from their real mother (or rarely, father, if they have one). Especially when they're armed with puppy-eyes stares.
Mine both believed me when I told them the money spigot ran dry when they turned 18. Both were enlisted at 17 and now doing well with families of their own.
Puppy dog eyes didn't get 'em anything.
/johnny