You can buy second hand 100g networking cards pretty cheaply. The caveat is that they only support older PCIe standards, so you need PCIe 16x to use them at full speed.
Please also don't forget typical NVMe drives are pretty fast now. Just two of them can nearly saturate a 100g link.
Personally I know a lot of people in IT field who have single mode fiber SFP28 networks. I'd say 0.001% - 0.01% is closer to reality.
Like 99% of the people I know who work in IT don’t have anything near what you’re mentioning. They spend $100 on all their networking equipment, not just a switch. They’re not laying fiber in their house. And outside of that group the number is basically 0.
I guess typical gateway drug is to get a 10g internet connection or 10g NAS at home and find out copper based cat6/7 is a lousy solution to actually make use of it.
Surprisingly high latencies (compared to fiber, that is) and noisy fans due to a lot of heat generated.
It's hard for me to picture doing something with an internet/NAS connection and caring about the extra percents of a millisecond copper gives you. And all the 10g cards amazon is showing me are fanless. Even if you need a fan, it should be enough at whisper-quiet speeds.
I say this because I am almost at this point (I run copper through my house) but was scared off on going full fiber. I know some who have, but it’s definitely really, really rare.
I had (well, still have) cat 7 in the house, while venturing into fiber as well. 10GBASE-T switches are noisy and surprisingly power hungry.
One big reason for fiber is a home lab. Transferring large VM images etc. is so much faster. Ability to run iSCSI fast is also amazing.
Single mode fiber is pretty nice. It's fast, has low power requirements and no need to worry about electrical issues. Prices have declined significantly. The only minus is that you can't have PoE, so the best option is to wire both.
Even top end wifi tends to only be around 1.2gbit.