My desktop PC turns 20 next year. I've never seen any need to upgrade it, went out of my way to build it with silent parts and it rarely if ever goes outside a single-digit CPU load (before anyone asks, software development and a bit of CAD work). I'll upgrade it when something in it physically fails, which means I'll need to replace it with new hardware with 5-10x the specs just to get the same performance.

My laptop is currently about two years into a typically 5-year lifespan, limited by when the keys start to fail rather than any need to upgrade it just because. The RAM in it is now worth more than the rest of the laptop.