> Cat8 is 40gbps and pretty cheap

Is it really though? People are selling cables, but 40Gbase-T hardware does not exist, and 10Gbase-T hardware is already crazy power hungry and the SFP+s heat up much you burn yourself if you touch them. Meanwhile USB-C 10 Gbps works on an iPhone.

Meanwhile, Coax is huge and stiff. Good high-speed USB-C cables actually have mini coax inside.