Educational support is usually regarded as a protective resource for vulnerable students, particularly those learning under social, economic, or psychological disadvantage. Yet support may become psychologically costly when it is experienced as overprotective, intrusive, or competence undermining. Drawing on self-determination theory, social support theory, and resilience research, this study develops the support burden model, which proposes that educational support may become burdensome when it protects students in ways that reduce autonomy, threaten competence, and limit opportunities for adaptive coping. Using a two-wave prospective survey structure with a six-week interval, the study examined vulnerable university students at baseline and follow-up (T1 N = 626; T2 n = 490; retention = 78.3%). Baseline-adjusted path models tested whether T1 overprotective educational support was prospectively associated with later autonomy frustration, competence threat, psychological resilience, psychological distress, and learning adjustment. Results indicated that overprotective educational support was positively associated with T2 autonomy frustration and competence threat. These two need-frustrating experiences were, in turn, associated with lower T2 resilience after baseline resilience and general educational support were controlled. Resilience was associated with lower psychological distress and higher learning adjustment. Indirect-effect estimates supported the proposed pathway from overprotective support to poorer adjustment through autonomy frustration, competence threat, and resilience. The exploratory interaction involving baseline self-efficacy was in the expected direction but did not reach conventional significance. Because the overprotective educational support scale is newly developed and the design is observational, the findings should be interpreted as short-term longitudinal associations rather than definitive causal evidence. The findings suggest that educational support should be empowering rather than substitutive, preserving student agency while providing accessible resources.