Based on personal experience, the older the hardware, the more resilient it is.
A lot of that is probably down to simplicity, but the fact that it's from a time when electronics were expected to be repairable and maintained is probably a big part of it as well. My Apple II Plus from grade school still works perfectly, and I've done nothing more than simply keep using it.
I recently acquired an IMSAI 8080 that had been sitting in someone's storage unit for the past decade. I used a variac at first to make sure I wouldn't fry any circuits, but it turned out to be in perfect condition, and went right back into action as if it were still 1975.
Meanwhile, my 2009 MacBook has long since given up the ghost—and of course, Apple has no interest whatsoever in supporting me to repair it myself. I wish our technology was still built to last, rather than built to replace every two years when the payment plan ends.
Apart from the main battery and any backup batteries that laptop would probably work if it were left in storage for a few decades. The power supply is another story, that probably would need to have its electrolytic capacitors replaced before it would work reliably (or at all). Laptops don't contain that much hardware which deteriorates in time, especially not when left un-powered to avoid electromigration becoming an issue. Switch-mode power supplies don't hold up well and their failure mode is often catastrophic, this in contrast to linear power supplies which start suffering from ever-larger ripple current as the buffer capacitors lose electrolyte over time. The main reason for this is that switch-mode power supplies have large electrolytic buffer capacitors on the high-voltage side while linear power supplies only have them on the low-voltage end. I've repaired many a 'boat-anchor' (large transformer-equipped linear) power supply by simply swapping out the buffer capacitors. Blown switch-mode power supplies usually don't come back to life by swapping capacitors, these often need to have some active components replaced before anything interesting (other than the rapid release of magic smoke) happens.
Bigger and more crudely build components probably play a large part. A Microprocessor from the 70s and 80s is made on much larger nodes than today's chips, traces and soldering points are bigger, PCB's thicker, almost all components sans resistors and wires were either bigger or build differently.
They have more material to play with while they decay compared to modern devices.
I'll bet good money that an IBM PC or PC XT that has been properly stored will boot up and be more or less as usable today as it was the day it was put to storage (especially the floppy-only models without an hdd).
Possibly, though I would still check capacitors and any voltage regulation (transformer and linear) to make sure it won't blow up suddenly because some wire coating rotted through.
> do my laptop will continue working in 30 years without maintenance?
Probably not, but same is often true for old computers.
Old hardware is easier to maintain. You can recap them, replace the failed memory chips and even fix cracks in the PCB by just running some extra wires.
You can do same to current modern computers as well, but it's nowhere near as easy.
> SSDs require power at least once per 1-3 years or otherwise they can lose the stored data.
This information needs to be better known. I assumed--and I think many people would assume--that SSDs would be an excellent medium for long term backups. Wikipedia confirms that SSDs aren’t good for long term storage:
"If left without power, worn out SSDs typically start to lose data after about one to two years in storage, depending on temperature. New drives are supposed to retain data for about ten years."[1]
A lot of that is probably down to simplicity, but the fact that it's from a time when electronics were expected to be repairable and maintained is probably a big part of it as well. My Apple II Plus from grade school still works perfectly, and I've done nothing more than simply keep using it.
I recently acquired an IMSAI 8080 that had been sitting in someone's storage unit for the past decade. I used a variac at first to make sure I wouldn't fry any circuits, but it turned out to be in perfect condition, and went right back into action as if it were still 1975.
Meanwhile, my 2009 MacBook has long since given up the ghost—and of course, Apple has no interest whatsoever in supporting me to repair it myself. I wish our technology was still built to last, rather than built to replace every two years when the payment plan ends.