Re: This makes no sense
“bigger roads just attract more cars”
well, duh!! "bigger" (actually wider) roads = more throughput = less traffic, making it more attractive to use private car vs public transport, so all other things being equal, it will obviously attract more cars. Whether that will, in fact make overall congestion worse depends on many many factors particularly whether you are widening just one road without widening feeder roads.
Anyway, to return to the bandwidth....
Bandwidth required for 4k streaming is about 25Mbps using already-current coding/decoding. Maybe you could for example code a video stream at source even better... but the current algorithms are already pretty good, I doubt you could squeeze more than 5%, maybe 10% bandwidth reduction. Then you have to encode it once at the server end and decode it 100 times at the user end, so each user device has to support both the new hardware requirements and software encoding. There's not really much rationale to need a new step-change-more-powerful GPU in every user device to save what is, ultimately, not a lot of bandwidth.
Just allow standards to gradually improve organically as they mostly always have.