CPU upgrades tend to make less of a difference than GPU. Gone are the golden days when each generation was twice the power, these days it tends to be small fractions, so I usually upgrade every two or three generations.
At the moment I have a 12700K and plan on getting a 15th gen early next year. That will be a new motherboard, CPU and RAM. Oh, and I need to up my cooling so I will be going from an air cooler to a water cooler. So it's about £1000, which I spent last year, but that was a GPU.
GPU's are too expensive now, so for the first time ever I will not be buying one this coming generation, I will miss out the 5000 and go for maybe the 6000 or even the 7000.
I recently upgraded two old PC's that I have. I used to keep my old gaming motherboards and CPU's and use them for media PC's. With the price rises in electricity and the good market in 2nd hand parts, I sold the 9000 series parts and bought two new motherboards and 12X00T CPU's. From now on I will not keep my old gaming PC's, the intention is to sell the parts on ebay.