It takes on the order of 100 years for well made modern CPUs to fail due to these effects, but poorly made CPUs could fail far earlier. There are likely some nonzero number of failures attributable to electromigration.
There are some people who buy overclockable parts and don't overclock them because they are more robust. It's unknown exactly how or why CPUs fail. Taking them apart to check is an extremely expensive endeavor. But sometimes they do.
Also, the chip obviously doesn't need to wear out to become less preformant over time. Reliability is perhaps the wrong word, I think quality would suit better.
But in any case, if you have one chip that decreases in performance 10% per year due to security mitigations and another chip that remains consistently performant, it is something to consider when shopping.
https://en.wikipedia.org/wiki/Electromigration
It takes on the order of 100 years for well made modern CPUs to fail due to these effects, but poorly made CPUs could fail far earlier. There are likely some nonzero number of failures attributable to electromigration.
There are some people who buy overclockable parts and don't overclock them because they are more robust. It's unknown exactly how or why CPUs fail. Taking them apart to check is an extremely expensive endeavor. But sometimes they do.