I'm still skeptical about any of my PC failures being the result of ESD. I've only had one hard drive fail (I guess I change them out for larger ones before they have a chance to die in most cases - though my server still has some originals that are plugged in and running 24/7 for 7 years now. No SMART issues so far so I have a feeling that when they go it will be catastrophic, not a gradual failure. Data is safe though, duplicated on another physical disk in the server AND backed up with a cloud backup (that works). Plus I'm about due to add a new larger drive and replace at least one of them anyway. I did have a power supply fry once, somewhat literally as the magic smoke did come out. Amazing it didn't take anything else with it, I replaced it and the same machine continued on for 3 more years. Doubt that was ESD as I don't tend to open up a new power supply and poke around. Salvaged ones from old machines - yes, I have turned some of them into power supplies for various uses with the addition of a switch to toggle them on, a load resistor, and some binding posts mounted to the case.
I can't say I've had many "mystery" crashes. Most anything that has happened to be has been fairly repeatable and usually a driver fault of some sort. Repeatable as in, driver install crashes system, reboot, restore to previous driver, repeat new install - same crash. I've perhaps just had good luck with various versions of Windows but my systems have always been quite stable, without periodic reinstalls, and the ones that are always under my control have always been virus-free. Same exact hardware, OS version, and virus protection software built for others - not so much. Stable hardware, but no matter how much I try to educate, they still manage to virus infect their machines on a regular basis. Once or twice I've had issues with expanding the RAM using mismatched memory - different specs on one pair of DIMMS vs the other, but with matched sets (or at least same type/speed) everything works fine, and the ones that didn't work work fine in a different MB. Not been an issue lately as the past few machines I've built I just went with the expected total RAM right off the bat instead of building it small and adding later.