Yeah I've never seen it either. However, I was curious if it was because instances were blocking it (as in fedipact).
Checking out Lemmy.world, I noticed threads is actually listed as a linked server. So at some point, lemmy.world has traded content with threads.net.
Though I can't actually find the content. And there don't seem to be any threads.net users (except a couple who wrote it in their display name as some sort of joke), so perhaps there are some threads users who are following lemmy communities but haven't commented (or aren't able to)?
I don't even have gigabit and if I try to download a game from Steam, it seems to eventually catch up to the disk and has to pause while the data is being written to disk. This is to an SSD.
If I was the only person in the house I wouldn't pay for gigabit, I'd just go for a couple hundred and that would be heaps. 100 would likely be plenty for most people too. But if you do a lot of downloading I probably wouldn't want less than that if I had the choice.