The rollout of 5G mobile technology has been anticipated to play a pivotal role in digital transformation, yet rigorous empirical evidence on its behavioral effects remains limited. This study addresses that gap by analyzing individual-level transaction data from South Korea covering October 2018 to December 2019. Employing a difference-in-differences approach with coarsened exact matching, we estimate the causal impact of 5G adoption on consumption patterns across digital and non-digital domains. Results show that 5G adoption increases in the frequency, spending amount, share, and diversity of digital transactions, while non-digital transactions remain unchanged. These effects are particularly strong in non-metropolitan regions, where improvements in network performance trigger larger behavioral responses. Within these regions, younger users and women show especially pronounced increases in digital engagement, while income-related differences are not statistically significant. By providing individual-level evidence on how advanced mobile infrastructure influences real-world consumption behavior, this study contributes to the literature on digital behavior, infrastructure inequality, and the digitalization paradox, with implications for business strategy and public policy.