Not really just Plex, in addition to powering 6 spinning drives (~50TB total), I also run Nextcloud, immich, Ollama (CPU inference, no GPU), home assistant, grocy, vaultwarden, jellyfin, sonarr, radarr, lidarr, prowlarr, flaresolverr, and overseerr. I run Plex on a separate Intel nuc10 (also included in that $10 of electricity) which has Intel QuickSync which allows me to transcode ~8 simultaneous 1080 streams to friends while leaving most of the rest of the CPU to everything else like running LLMs on the CPU (it's cheaper to run larger models on a slower CPU with lots of RAM compared to buying a GPU with a matching amount of vram).

So yeah if you don't care about n+2 double redundant disks or sharing with more than like 5 people or hosting other apps or running AI while people are streaming then yeah you should totally get something less power hungry. Just the Intel nuc10 I use for Plex (but not media storage) has a TDP of 25W so just that would lower the electricity cost to like $2.50/mo.

I mainly chose to just use the cost of my whole setup's electricity as an example because it didn't seem worth it to think about how to split up the idle wattage between services especially when it's gong to come in at way lower than the combined cost of all the major streaming services anyways, plus I don't want anyone accusing me of needing to underestimate to make my point - even if I overestimate, it's way cheaper.