How long should components last?

one of my 1st amplifiers... Bryston 4b NRB was purchased 1990 and still works. I use it as an amp connected to a Denon home theatre receiver to drive the main front speakers . Still use on a 2ndary system a BAT VK 30 preamp. Sound is tiull warm and airy. Gives you an idea how long quality products can last. Really depends on how well you maintain your product and what type of product it is. Class A products run hotter so recapping and servicing are essential.. tube products will require constant monitoring for microphony. I have a California Audio Labs CD player from the 90's that will still produce high quality audio. Some products are known for their longevity. Budget at least in my experience is not always a determining factor into electronic component  longevity. And Yes i will have to agree with allenf1963 that North American products are built to last. I have friends that spent 40K for amps Germany & Switzerland that have failed in less than 8 years of use.

I was thinking it was a design issue, but do high-end components have “lemons” like cars?  

In contrast to the AV receiver experience I wrote about, in 1980 I purchased a new Mcintosh MC2125 power amplifier.  In about 2005, I had it refurb'd with new caps, an LED replaced, and a few other minor items replaced.  The cost was very reasonable.  In 2022, I traded that fully functional and cosmetically almost pristine amplifier for a newer amplifier.  Most of my electronic components (Rogue, Odyssey, Lounge Audio) were made here in the USA, and they seem to be built for the long-term.

I have a variety of components that I bought new, in 1975, or earlier, that are still operating in my vintage system after refurbishment. My first ARC amp from that year, a Dual 75a, is still in good fettle, but dormant- I would recap it, have a full set of older replacement tubes and a few other odds and ends that I bought from ARC years ago (like the barrier strip terminals, which break). 

The amps currently running in my vintage system were built in 1959 and 1961. They were refurbished twice, most recently by the late Bill Thalmann. 

I expect a lot of this gear to last a lifetime. I’m now in my 70s, and though some of the gear was more expensive than beer budget at the time, we are talking about decades old expenditures (leaving aside routine maintenance, and of course, sourcing good tubes, which is a PITA). To me, that’s a better expenditure than replacing consumer electronics every ten years. Then again, when I bought a lot of that stuff, it also wasn’t oligarch money. I was still in college when I bought that 1975 system and paid for it out of savings because I also worked part-time. I don’t know how that would work with uber-priced components today. 

My Lamms were purchased in the aughts, early serial number ML2s. They have been serviced over the years, but nothing drastic-- in fact, when I lived in NY, we’d drive them over to Deep Brooklyn. Now, I’d have to pay for air freight from Texas (to Florida, where Lamm relocated after Vlad passed). But still- those amps, as Vlad once told me, can last a lifetime. 

Vintage guy here, my pre & power amp are 50 years old, have been refurbished by me 2 years ago, expect this stuff to outlive me.

Some of the new surface mount gear, with cheaper power supplies and op-amps, is mostly disposable. Sadly think streamer are a disposable product. As soon as the software leaves the app store, they are useless. 

If taken care of, most things should last at least 10 years.