There are young ones who are successful who own luxury cars, sometimes more than one luxury car. The problem they have is that they cannot sell it themselves.
http://www.interestingcarfacts.co.uk/jaguar-xjl-showcase/
So what happens when they want to sell their cars? They have to have an adult who will stand for them and contact car buyer willing to buy the car, or the would go online and search for sell my car