Photography is a hobby of mine and often when discussing high end nikon cameras and lenses the comments get made like "it will outlast you". Which is true at-least about lenses,
I've just been through, let's call it, a relevant experience. I decided to get back into photography after a few years' hiatus.
I was planning a holiday which would involve wildlife photography, so I figured it would be a good idea to test my equipment and re-familiarise myself with how it all worked.
It didn't start well. My Canon 100-400 L IS threw intermittent error codes whenever I turned IS on. The repair centre diagnosed a faulty IS unit, but said the lens was no longer supported by Canon. No spare parts available. I sold it as-is and bought the mk II version to replace it, which turned out to be a much better lens anyway, but it was an expense I could have done without.
A few weeks later I went out with my 24-70 f/2.8 L, and came back to find some shots significantly mis-focused at f/2.8. Turns out this is quite common and is due to mechanical wear causing slop in the mechanism, and should be easily sorted with a routine service. But you've guessed it, no longer supported and no parts available. Once again, I sold it as-is and replaced it with the mk II, which is slightly smaller and lighter but otherwise barely any different as far as I can tell.
Feeling neglected, my 50mm f/1.4 prime decided to take a flying leap out of the cupboard where I store my kit. It has a focus mechanism that's oddly fragile, but fortunately spares are readily available and inexpensive, and there's a really good video on YouTube showing how to fix the exact focus issue that it developed as a result of its drop to the floor.
In the meantime I sent in my 5D mk III for service, whilst service is at least still available for that model. I still remember buying it new, and there's barely a mark on it... can't quite believe how old it actually is already. A dodgy rotary encoder needed replacing, which was surprisingly inexpensive, but it was still over £200 all-in to get it shipped, cleaned and calibrated. Still, I have a camera that should last well now, which is just as well as it can't be too long before spares for that model also dry up.
I also cleaned the focus screen of my 1DX mk II, and thought I'd scratched it in the process. (Note: this is *very* easily done - though the 'scratch' in this case actually turned out to be a fibre from a cotton bud, which was a relief). Nevertheless I was dismayed to find that the standard focus screen for this camera is - you've guessed - already discontinued, and the only place I could find a replacement was an Ebay seller in China. IMHO it beggars belief that such an easily damaged, critical part of a 1D-series camera should already be unavailable as a spare.
Finally, at least for now, another unfortunate accident befell my 70-200 f/4L. This was by some margin the oldest of all my lenses, and surprisingly, it's still under service support. Except in this case, that's irrelevant, as the cost to repair the apparently minor damage to the focus mechanism exactly equals the cost to buy a good used replacement. Odd, that.
My advice? Don't expect kit to last forever, because even if you don't use it much, even a minor problem could easily write it off if spares are no longer available. I've spent a small fortune over the last few months, on kit which should have been easily fixed, but couldn't be due to the lack of spare parts.
Instead, go out there, use your camera, and get the best value out of it that you possibly can.