Including food, utilities, commuting costs, etc. while living with parents? These cost more than $0, though typically less than what it would cost for the student to live in his/her own.
Decades ago, it was more possible for a student to self support living on his/her own with a high school graduate job and pay the small state university tuition and books costs to attend. Now, of course, high school graduate jobs do not pay as much relative to the cost of living, college costs a lot more, and college financial aid assumes that the parents will pay until the student is 24, married, or a military veteran.