I remember when my son got out of high school, he had a job, but did not want to continue his education and he wanted me to treat him like an "adult", as in let him do his own thing, not impose on "his" life.
I told him if he wanted me to treat him like an adult he had to act like one and start paying me rent, pay his car insurance, cell phone bill, etc.
He agreed and that was the best responsiblity teacher he ever had...after having to work and actually pay bills with his little paycheck it was a huge encouragement for him to return to school as well and take an active interest in growing up!
Sometimes learning the hard way is the best lesson.