Psychological theories of media use often assume that subjective motivation affects observable behavior. Using video games as a test case, we examine this assumption by pairing repeated self-reports of motivation with objective digital trace data at scale. Across two datasets comprising tens of thousands of hours of gaming behavior, we test predictions derived from self-determination theory and the Basic Needs in Games (BANG) model, which posit that autonomy, competence, and relatedness experiences drive engagement. Study 1 (preregistered) analyzes 11k daily observations from 555 U.S. players with 30 days of multi-platform digital trace data. Study 2 (exploratory) examines 102k sessions from 9k PowerWash Simulator players, linking in-game experience prompts to behavioral logs. In both studies, need satisfaction was robustly associated with subjective states but showed weak or null associations with short-term gaming behavior, including subsequent play, session length, and return latency, across extensive preregistered and robustness analyses. These findings reveal a substantial motivation–behavior gap and suggest that SDT-based accounts may overestimate the role of need satisfaction in explaining when or how much people play. Data and code are available under a CC0 license at https://doi.org/10.5281/zenodo.18352505.