you describe the results of an optimal scenario: low use, low humidity, a constant mild temperature, no power surges or outages, etc. fans, hard drives, and disk drives all have moving parts which can fail. capacitors on a board can fail, as well as batteries. dust build-up is also a thing and I have had spiders camp inside pcs before. degradation over time is inevitable for everything but proper care and maintenance always helps
I have a 14 year old laptop in my closet and a tower in the living room that's like 16… both still work somehow and I know the tower was rarely maintained and not shut down properly until it was given to me… and I commuted with the laptop for a few years
it blows my mind when people tell me their computers only last them like two years. what the fuck do they do to these machines?
I leave my computer on most of the time because it doesn't hibernate properly thanks to a trash motherboard. and the noise of the fans helps me sleep better
in the past I thought about setting up remote access to it since it is on all the time, but I'm always at home these days so there's no point