Advances in Information and Communication Technologies have dramatically changed the role of users and resulted in unprecedented amounts of information that enrich users' awareness about their environment and its resources. While this broad awareness for (low-priced) limited resources can bring benefits, it also intensifies competition phenomena in distributed and uncoordinated environments, shaping, in turn, the users' decisions whether to compete or not. This paper investigates the uncoordinated resource selection problem and discusses how competition awareness shapes decision-making under different levels of rationality. The case of strategic and fully rational users provides benchmarks and "reference" understanding, against which other more realistic or human-centric cases are compared.