On planet Jung dwell the Jungians, sapien-like beings who need only a single cup of a rare liquid to live an entire lifetime. For humans, that same cup grants twenty extra years of healthy life.
Human just landed on the planet Jung and discovered the liquid--what happens next?
If ever we are able to journey through the interstellar medium, we ought to have achieved immortality by then. We'll probably live as deincarnated beings in virtual worlds, free from any desire to grow exponentially, having realized this is deeply unsustainable and pointless once you have mastery over physical reality.
Read Diaspora by Greg Egan, perhaps it can cure you from this simplistic vision of the far future we have inherited from the 50s pop SciFi books.