generally speaking, its more valuable if the cost of electricity used is lower than the cost of getting better internet (e.g living in the bumfuck no where).
say if your isp gives you a 250gb cap and costs 50$ per 250gb (just throwing out numbers), it might make sense to use less data in the stream quality, and upscale it to a higher resolution using GPU as a cost saving measure.
4k is not the dominant resolution for some media like twitch streams. There are also lots of people who still don't have Internet fast enough to stream native 4k. It could help with older YouTube videos, as well.
I need to look for the statistics again but most media is still served at 1080p. If you look at the most popular YouTubers however the skew is towards 4k because Google wants to tout that number, however the bitrate is comparable to 20mbit 1080p