Well, no I'm not. You're right. I miscalculated how much data was needed for video streaming. Even multiple simultaneous hi-res streams should stream fine with 1GbE.
But as an abstracted idea, you might want high throughput within your LAN for some reaosn, even if an ISP doesn't offer 10Gbps to your house.
File transfers between devices is one reason. With NVME R/W speeds you can easily saturate 1Gb networking equipment. I think 10Gb is more than most people need most of the time but it would still be nice to have if it weren't so expensive. I just bought a small 2.5Gb switch to connect my server and PC together since both have 2.5Gb NICs and that seems to be a happy medium.
My gigabit connection is good enough for my NAS, as the read speeds on the hard drive itself tend to be limited to about a gigabit/s anyway. But I could see some kind of SSD NAS benefiting from a faster LAN connection.
There are multiple ISPs that offer 10Gbps Internet service in Japan and South Korea, I imagine other densely populated cities might have them also. There is also the Swiss ISP that offers 25Gbps Internet service since 2021.
Realistically with my 1Gb connection, it’s always the outside restricting speeds. I seem to get the speed I pay for but every download or stream is throttled
Steam downloads consistently saturate my 1 Gbps connection, but it's still fast enough for me. Had it a year now, still not really used to things going that fast.
I connect my primary and backup servers on 10G directly via a crossover cable for transferring ZFS snapshots. No actual 10G switches or anything at the moment but if I add any more servers I need to back up I'll probably get a small 10G switch to put in between.
I do have 10 Gbps, I pay $35/mo here in Japan (not even a big city like Tokyo, this is a depopulating, rural capitol)
More importantly, even my 5 year old, 4-bay spinning rust Synology NAS can saturate 2.5 Gbps copying files. With soldered storage in modern machines, faster networking is cheaper than replacing my whole machine