Nerds like to argue but this the easiest set-it-and-forget it way is to get a raspi or old PC and put some home server OS on it like CasaOS, Umbrel, or TrueNAS. Then get the following apps:
- Torrent app like Deluge or qBittorrent
- Prowlarr - Searches torrent sites
- Radar - Manages movies
- Sonarr - Manages television shows
- Plex - organizes downloaded media and streams to your devices
- Overserr (optional) a friendly GUI for requesting media.
Trash guides are useful for getting it all set up. There is a learning curve but once it's up and running you don't need to think about it.
I think about this exact topic a lot and I think you are mostly right, but I also think that open source replicators would be an agent of change, especially if one could be used to manufacture parts to make another. Of course, without land to make things on conflicts will arise. But once the need for money is removed some people will choose to "opt out" of society and start building a parallel one similar to how the open source community exists alongside closed source software.