Can't pay vs.don't want to pay?
First, as mentioned by other counselors on this site, this particular scenario should not ever happen. Applying to colleges hoping that scholarships and financial aid will cover all expenses is risky, at best, and totally ill-informed. Colleges expect families to bear the costs of a college education. I can understand a student exploring a couple of schools that may be more expensive just to see the results; yet, only applying to schools without any regard for financing is counterproductive. Students and families rarely receive ALL the money they think they deserve (or need) in the financial aid process, albeit, plentiful funding is available to very low-income, high-achieving students.
Options? Besides the community college route already mentioned by others, I suggest taking a year off to work, travel, or participate in a community service project. Upgrading one's personal profile/resume, completing more outside reading, and/or traveling abroad to gain valuable awareness and life experience can be viable options. I've had students do just these activities, reapply the following year, and receive even better offers of admissions and financial aid awards. .
Other students join the military reserves, which can provide valuable financial support and also give one an opportunity to serve our country.
No single option is best. Sit down with a college consultant/counselor and weigh all of the factors and options before making a decision.