Student debt is a main driver of poverty and homelessness. Solving the student-debt crisis will reduce the poverty and homelessness and reduce the burden placed on programs meant to deal with those issues. It may be cheaper in the short term to just pay into those services, but why should people suffer before getting relief, when suffering could be prevented altogether?

Also, your impression about what college students actually do is completely unrepresentative of the experiences of those who are grateful for the opportunity to have an education, i.e. the people who would most benefit from having the costs of their education subsidized, i.e. those who go in with few opportunities and come out with many more. The only people who party are those who could already afford to live their lives normally after they graduate, or the people getting degrees in high-return fields (i.e. business and engineering).