This study investigates how the interaction of teachers' personality traits and demographic characteristics shapes their perceptions of sustainable careers (PoSC) within the framework of Complex Adaptive Systems (CAS). By looking at the Big Five Personality Traits along with conditions like age, gender, marital status, and parenthood, the research uses Qualitative Comparative Analysis to understand how these traits combine. Data collected from 315 teachers across Türkiye yielded seven distinct configurations that contribute to high PoSC. Across these, agreeableness, conscientiousness, and open-mindedness emerged as core traits, while extraversion and negative emotionality demonstrated varying influences depending on demographic context. The research underscores the nonlinear, context-dependent nature of career sustainability and highlights equifinality--multiple pathways leading to the same outcome. By integrating sustainable careers theory with CAS, this study offers a novel lens to understand how individual and systemic conditions co-shape career experiences in education. It also offers useful information about developing differentiated support strategies based on personality-demographic interactions, particularly within the centralized and culturally specific context of the Turkish education system.