CramBoom
Classy Science
Some of my videos are in 1440pYeah it does, I guess most well known Youtuber's will upload in 1080p. ImAnderZEL has a decent gaming channel, he uploads in 1440pHis internet must be God-like.
(I upload from my school
)It also depends on the video. If you are vlogging or making short films, 720p is acceptable, but for gaming, animation, etc it should be 1080p, because lower resolution is more noticeable.
His internet must be God-like.
It can be noticeable, but I could upload in 1080p from home, I would. I live in the middle of nowhere in the UK. 
, When uploading I have to devote a whole night to it, and my computer being about 2m from my bed it gets pretty frustrating. Plus recording at 720p saves space like you said and reduces rendering times.
I have noticed a lot of youtubers only do 720