As social media increasingly operates within algorithm-driven attention economies, clickbait has become a pervasive engagement tactic. However, prior research has not fully explained the psychological mechanisms linking clickbait to downstream consumer behavior. Existing studies have also largely treated clickbait as an isolated persuasive cue, overlooking its dynamic interactions with other elements in social media ecosystems. Drawing on psychological reactance theory (PRT) and uses-and-gratifications theory (UGT), this study develops an integrated framework to examine when clickbait harms versus facilitates consumer responses. Across four experiments, we test a sequential mediation model in which perceived intrusiveness and advertising avoidance transmit the effects of clickbait on purchase intention. We further introduce message appeal congruence as a key boundary condition. The results indicate that clickbait does not uniformly produce negative outcomes. When headline-induced motivations align with the gratifications delivered by the content, perceived intrusiveness and reactance are attenuated. When they are misaligned, advertising avoidance increases and purchase intention declines. This research advances the clickbait literature by shifting attention from static credibility judgments to dynamic goal-directed processing and by identifying gratification fulfillment as an upstream regulator of psychological reactance in social media contexts.