While the story is satisfying, the in-universe thing I had a hard time accepting was the extreme time dilation. Spending hundreds of years fighting or partying is something that would lose its novelty pretty quickly. For a few characters, spending 70 years in prison in solitary confinement would probably have resulted in some sort of mental illness. The same story could have been written compressing the time into just a few years, making it more believable in terms of human nature.