The Cascade of Exclusion: A Mixed-Methods Study of Welfare Inequity and Its Foundational Determinants Among Thailand’s Homeless Population

Achieving sustainable development (SD) and enhancing urban quality of life are undermined by the systemic exclusion of marginalized groups. Despite the global expansion of welfare systems, a welfare paradox persists, wherein universal policies often reinforce exclusion. This study investigates this paradox through a mixed-methods analysis of welfare inequity among homeless individuals in Khon Kaen, Thailand. Combining a quantitative survey (n = 202) with in-depth interviews of homeless persons and state officials, we model the structural nature of this exclusion. Results reveal systemic disparities by gender, age, and displacement causes. Critically, a predictive model identifies housing and education access as foundational determinants, collectively explaining 89.9% of the variance in economic inclusion (R2 = 0.899, p < 0.001). Qualitative data elucidate the mechanisms behind these statistics, highlighting how the lack of official documentation and institutional stigma sever access to the broader welfare system. We conceptualize these interdependencies as a foundational capability cascade, where deficits in core domains trigger compounding exclusion. By integrating statistical modeling with narrative evidence, this research provides a robust framework for social exclusion and offers an evidence-based roadmap for designing equity-focused policy reforms that are essential for inclusive urban sustainability.