Remember you can get an HP Prodesk G3 400 or some such for $60 refurbed with far more hardware capabilities if you don't need the portable form factor, gpio, or power consumption.
Right, I agree, but electricity prices are variable and location dependent, for example, it doesn't cost me 30c/kwh, it's more like 5 cents and 3 cents depending on the time.
With that logic, the $20 in difference of $30 per year vs $10 per year of Pi is fairly meaningless for performance boost I am getting.
If your electricity is expensive, sure, but I imagine the performance boost would be worth it for an actual homeserver that a G3 can make vs a tinkering/fun project you can make with a Pi.
You're comparing a CPU that became generally available in 2017 or earlier (i.e., the 7th-gen or 6th-gen Core CPU in the Prodesk G3) with a more much recent CPU.
It's actually a better deal for home servers.