I always wonder how many system crashes that we put on the software or the OS are actually just sub optimal components. Computers are so complex and so fast that just a little bit of instability can probably lead to data corruption.
Most people using computers aren't technical enough to be able to discern these things, however, and many buy the cheapest thing on the shelf and so these subpar components persist.
Wild troubleshooting adventure.
I've had one case of Corsair memory which went faulty after a year (was replaced without question by the supplier) and around 3 PSU failures.
However, on the 3 times I've done upgrades (typically motherboard + RAM + CPU) in that time I've been able to keep my existing PSU without stability issues.
So I wouldn't say it's "insanity" to keep your current PSU when upgrading, but based on your experience if I had stability issues it may be the first thing I test.
No need to replace a quality PSU until you start having issues.
Now, I'm not someone good at maths or physics, so maybe, somehow, it's actually more likely than not that the worse OS gets to run when there's worse solar activity going on or whatever else has en effect on my hardware, which also doesn't seem to affect memtest for some reason.
But the likelihood can't be that high. Can it?
If you've got an IO-MMU and everything aligns properly, devices can't DMA to the wrong place anymore, which might make it easier to track things down.