["International Journal of Economic Theory, EarlyView. ", "\nAbstract\nSocial platforms have triggered global systemic crises in data security and tax governance, with acute contradictions between operational models and regulatory frameworks—urging exploration of sustainable paths via collaborative regulation. This paper constructs a differentiated duopoly model to comparatively analyze, from the perspective of regulatory mechanisms, the impacts of different regulatory approaches on digital services and regulatory strategies of social platforms within a platform ecosystem composed of the government, social platforms, and users. The results show that the equilibrium strategies of both social platforms and the government are contingent upon the marginal value of user personal data obtained. Counterintuitively, government regulation may exhibit heterogeneous impacts on two homogeneous social platforms. Moreover, compared with government regulation, collaborative regulation does not necessarily lead to a win‐win situation. These findings provide important theoretical foundations and policy prescriptions for data market regulation and sustainable development in the platform economy.\n"]