That can be done on hardware that quite a lot of people basically just have and don't use 24/7 to the max - because it is their gaming machine or their programming and compiling workhorse, for example. Of course you are paying for additional electricity but even with napkin-math instead of a "proper" calculation, you are unlikely to pay more for running your own instead of something commercial (and that can be offset further with some of the "modern" electricity contracts and/or PV and battery storage). Especially if we are talking about a stack that runs most of/all the time when you are not using your machine and makes LLM calls regularly while running.

The work in software/admin to get whatever you want set up is similiar no matter which infrastructure you use.

I, personally, do use frontier models in the cloud for a lot of (meta-)cognitive analyses that are heavy enough to have me run against the limits of payed accounts regularly - so I'm neither a Luddite nor stingy with cash in this case.

However: I have pretty good experiences with local models as well. My solid but hardly extreme desktop (with one RX 9070 XT 16GB) mostly serves gemma4:12b and specialized models (embedding) to my local network. This is for general use like simple queries, simple code, reformatting and the like but also for two specific tasks that are permanently running:

a) It's connected to Home Assistant (as a second stage after very simple "turn light XY on" commands which get processed without LLM). So, I can mumble into my smartwatch "computer, how much gas do we have in the warp core and how much energy did the bussard collectors make from the cosmic dust today?" (or describe a more complex light scene or create an automation I want or whatever). The phone transcribes that - with a local model on device - and fires it to the desktop who has agentic access to HA, looks through the sensors and data, sees that I've tagged my solar panels and battery with nerd vocabulary. It makes the right conclusion, converts a few units and gives me back a nice overview. All hands-free while I'm sitting on the toilet.

b) It's the LLM backend for a personal radio station run by a fleet of nerdy/quirky AI DJs who's archetypes are represented more than well enough in the latent space of the "small" model to produce funny results. The DJs can produce consistent, individual segments and programs, run a playlist that works well for me (based on multi-layered audio analysis that also uses local LLMs), respond to song wishes and generally produce much better recommendations than Spotify ever could for me. And you can also put multiple of them in the "studio" to create hilarious crossovers that you would not get from a commercial entity because the IP owners would rather shoot each other in the face.

All of this doesn't even max the available resources, so I can shovel F5-TTS into the VRAM as well and have all my DJs have good, locally created voices (or voice clones of Captain Picard and Han Solo, if I wanted to) based on zero-shot voice cloning.

--> Far from "unusable". It just depends on the task. And I neither have to hand my keys to the Navidrome server nor to my Smart Home to any entity outside my local network.