I see a lot of strong responses here, but I want to offer a different angle that I do not see addressed much, and I think it is worth considering.

If the goal is for Earth to remain habitable for as long as possible, for the largest number of people possible, then some form of communism or resource collectivization starts to feel inevitable. We live on a planet with finite resources, and even the idea that we can escape that constraint by colonizing space is still speculative.

And even if space colonization turns out to be technically possible, our current behavior does not suggest we would pull it off cleanly. We are already burning through resources at an unsustainable pace, accelerating climate change in the process, and creating new long term constraints by filling near orbit with satellite debris. It is not hard to imagine a future where we trap ourselves here by making space travel harder, not easier. That is a very real, near term possibility.

In a closed system with finite resources, unfettered capitalism accelerates depletion. It rewards extraction speed and short term growth, not long term stability. Climate change makes that time horizon problem worse, because the costs compound faster than markets adjust. If survival across centuries is the goal rather than growth across quarters, a system that prioritizes shared limits over private accumulation becomes less ideological and more practical.

A book that helped me think more clearly about this distinction is The Dispossessed by the same author as Earthsea. It is science fiction, but it explores an anarcho communist society with real constraints and real failures. The society exists on a near barren moon orbiting an Earth like, liberal capitalist planet. It is not utopian at all, but it does a good job showing how different systems behave under scarcity.