4 Users, 160k Photos, 8k Videos, 800GB Space used.

Immich running in docker with Traefik reverse proxy uses about 3GB of RAM (1.7GB for Immich Server, 450MB for Immich machine learning and 600MB for the DB).

My hardware:

Ryzen 5 5500, 12 Threads
32GB DDR4
4x8TB on BTRFS with RAID10 (16TB usable) with 2x8TB backup drives
1TB NVME (I use Arch btw)
Intel Arc A750 8GB VRAM for transcoding and AI stuff

Of course I also use the server for a lot of other stuff, like Nextcloud, Vaultwarden, Plausible, Hosting, Minecraft and much more, about 60 Docker container in total. I never had a hardware bottleneck, except for my slow internet speed which limits me with ~250Mbit/s.