I had very few failures, but my boards are from 1999 and newer, video and sound cards from 1996 and newer. I did save a few boards by replacing electrolytic caps, and managed to cobble together one working gf4 ti4200 from two dead ones by painstakingly soldering the tiny smd components. It helps if you can solder.

But the longer I tinker with old hardware, the more appealing emulation starts to look. Especially Dosbox and Glide wrappers. If in 5 years my old hardware starts dying, I probably will not spend the time and money replacing it.

Plenty, because that's what I'm looking for. Repairing faulty hardware is my hobby in the hobby!
But I see your point, it's frustrating when you spend money on something that doesn't work or fails quickly.
Luckily most of these failures are fixable if you are willing to get your hands dirty.

Not so much complete failures but I have been getting annoyed with imperfect parts. So many of my motherboards have some sort of issue that doesn't break them but means they aren't 100%. (Ports not working, RTCs losing time because of weaker external batteries etc..)

I guess I've been pretty fortunate in this regard. So far, all I had was a bunch of hard drive failures either due to getting bad sectors or simply from wear and tear.

Also, my 17" Samsung CRT had lost the ability to display the color red, but thankfully, a service technician was able to repair it. It was just due to some solder joins going bad with time, and reflowing them fixed the issue completely.

Same here OP. I've had over 12 boards fail in the course of 18 months. I've started to replace capacitors (all of them) and in some cases MOSFETS on boards I use (or plant to use) frequently, I'm hoping that will prevent failures. I've also purchased anti static bags for all my stored hardware.

I recently had a failed RTC oscillator. Never saw one of those before, I'm not sure how to test that at all, was just blind luck that I was able to track it down.

I find failures come and go in waves for me. Usually leads to a paradigm shift in my entire collection of PC's really.

I like to stockpile some spares spares for anything rare/expensive or getting there . I only have 1 actual "finished" DOS/Windows 9x retro machine, 1 testbed DOS/Windows 9x retro machine, 1 XP retro machine (currently in storage) and 1 Windows 7 "retro" machine .

I have spare mainboards for all of them, spare video cards for all of them and spare sound cards for most of them .

I am a hoarder, I admit it .

This year I've lost
My very first PC, suspect the original Dallas RTC has given up after 25 years as it didn't like been unplugged for extended periods of time.
Prolient 1600, Suspect caps as wouldn't always powe on on at first button press for while now.
ML350 G5, failed VRM (of course it's the one on the M/B not the socket one)
Asus P2B-DS, Failed SCSI drive for a while but now doesn't post. Haven't Investigated at all yet
Asus P4P800, Corrupt BIOS. Recovery disk doesn't work.
And just last week my POD83 HDD failed, again it's been struggling for a while now.

So some of these have been trying to tell me for a while now they aren't happy but this year seems to be pretty bad. Normally I may just get a failed HDD, stick of RAM or whatever in a year in 1 system