J.W.
Once my kids hit 18 they have to have direction to stay in the house. Both started out in college but my oldest dropped out after a couple years. Son of a rich man syndrome. :p Fine, go work for the family! He didn't want to for a while and he was given his marching orders. He works there now and maintains his own home.
It isn't easy saying you are going no where and you will not do it in my home but it must be done. Allowing it to continue is clipping their wings, handicapping if you will. Loving a child means doing what is best for them, not what seems easy.