I got 4K TVs for both of my kids, they're dirt cheap-- sub $200. I'm surprised the Steam hardware survey doesn't show more. A lot of my friends also set their kids up on TVs, and you can't hardly buy a 1080P TV anymore.
Does Steam hardware survey show the resolution of your usual desktop, or your gaming resolution? eg I run at 4k in Windows normally, but quite often run games at 1080p.
I'd bet it's either the native display resolution or whatever you had for your desktop when submitted. They're able to gather all kinds of hardware specs so I'd lean to the native resolution as the most likely answer.
