My laptop has always been entirely secondary use PC, so they don't get much of regular use and still less anything which could be considered heavy use.
At least for what can be considered resource demanding for that moment.
First one was Acer Travelmate 803 which I think I had for seven years, after that it went to sister who used it for IIRC 3+ years.
Now I have (as model 10 year old) Lenovo ThinkPad T500 bought IIRC ~8 years ago.
Because of problems in showing higher res video taken with camera and drone I've now ordered X1 Yoga to replace it.
For light use like word processing and web surfing it could certainly be still perfectly working for years with few easy/minor updates.
With proper handling it certainly wouldn't be breaking mechanically soon.
And Lenovo certainly didn't put any sponges inside it to collect humidity and corrode PCB, unlike some other company.
Of course if you buy some cheap model made from the cheapest materials, it might start rotting by itself even in the most careful use.
But quality laptop can certainly last long time mechanical construction wise.
Also if properly designed and built electronics shouldn't fail fast in normal use.
Though of course cooling system would be good to clean once per some amount of usage hours, especially if environment isn't very clean.
Even if CPU can throttle itself to prevent "core meltdown", dust could wear down fan and unnecessary high CPU temperature shows in temperature of surrounding components.
