I suppose it is possible she is simply eccentric, and wanted to live out the scenario, "If only I knew then, what I know now, everything would have turned out better". But, yeah, more likely she was doing some kind of shady predation to sell drugs or to trick or solicit kids into doing porn or some such sick shit. The article quotes the school admins as saying she was enrolled while accompanied by her supposed and assumed (parental) guardian, so she was not in it alone.