He is 19 years old, has a job but contributes absolutely nothing to the household. I believe that the only responsible thing that we can do is to tell him to get out of the house and leave the car. If he wants to be an adult, let him be a full-fledged adult. He says that he is over 18 and that we can't tell him what to do. There are kids like this, and happily oftentimes they straighten out after a couple of years.
Tough love is the only way to go.
You have got to be kidding me. Play by our rules or get out. I understand that it may be extremely difficult, but it's the only way that this boy is ever going to learn responsibility. While buying a house is more of a lifestyle judgment than it is an investment, the idea of purchasing a home that is so far over your means that you will have to restrict major portions of your life in my opinion makes very little sense. While I understand and sympathize with your feelings of wanting to move up, putting that kind of strain on you for several years, in my judgment, cannot be justified.