Recent initiatives worldwide have promoted the "growth mindset" to improve educational outcomes. However, the effectiveness of this approach remains controversial. This research presents novel perspectives by investigating the natural effects of growth mindsets on students' academic performance trajectories from university entrance to completion. Longitudinal analyses involving 915 students, 6,918 student-term, and 33,607 student-course observations, reveal previously unexplored relationships. Transcending the dichotomized debate of whether growth mindsets are effective, our findings reveal that students with stronger growth mindsets initially outperform their fixed mindset counterparts; however, this advantage diminishes over time. Additionally, students with growth mindsets are more adept at navigating unfamiliar academic territories. Importantly, both growth and fixed mindsets are associated with higher academic achievement, but a lack of clear mindset is linked to poorer outcomes. Our study underscores the importance of considering these factors in educational institutions that aim to foster growth mindsets to enhance human capital development.