Why does Eugene think he got the better end of the deal?

Eugene believes he got the better end of the deal because Vincent lent him his dream, which refers to the opportunity to pursue the life that was denied to him due to his genetic condition. In the context of the film "GATTACA," Eugene, who was genetically designed for greatness, becomes a character who has to live with the limitations imposed upon him. By assuming Vincent's identity, he not only experiences the life he desired as a genetically superior individual but also the essence of Vincent's ambitions and aspirations. This exchange symbolizes a deeper connection between the two characters, wherein Eugene benefits from both Vincent's status and experiences that he could not attain on his own. This choice captures the core theme of the film about identity, ambition, and the societal implications of genetic engineering.