I had all of that. Ran into intermittent random crashes about a year ago. After a year of not being able to find a cause I found a thread of other 5800x users running into the same problem. (For the record this was with a high quality PSU, a very very light overclock, and temps were fine throughout that time. Also while I'm not a true IT professional I do know my way around a computer, and the most in depth error logs I could find, which there were very few of, pointed to really low level calculation errors.)

After finally giving up and just buying a 9800x3d I gave the system to my friend for a huge discount, but after reinstalling everything the CPU never booted again.

While what you say is generally true, it is also sometimes the case that some parts are just slightly defective, and those defects might show with age. It's the first CPU I've ever had that died on me (other than a 9800x3d but that was an MSI mobo that killed it,) so I don't really hold it against them. And I'm very happy with the 9800x3d. Its amazing the difference it's made in games.