By how much does an overclock reduce the lifespan of a CPU?

[Geotropism]

I have an i5-8600k clocked at 5GHz at 1.31v. I've run an hour of AID64 and 30 minutes on Prime95 (p95v294b8.win64) so I think it's stable enough. By how much does an overclock reduce the lifespan of a CPU? Should I reduce the overclock to maybe 4.6GHz at 1.1v - 1.2v to increase it's lifespan? I know i'll upgrade long before the chip dies but I don't want to sell someone a chip that will just die after a few months.

[Firewrath9]

LIFESPAN increases by 2 years.

it increases how long you can use it until its so shitty it cant do anything.

[Macxd]

I can't say for sure how much it reduces total life span, but i do know is that as long as temps are under control its really high long sustained voltage that will degrade a cpu's life span. So if you can keep your voltage as low as possible to keep your oc stable that will always be better.