Your SSD comment aside: not everyone lives alone; during the lockdown we had four people using the network simultaneously during the day, plus of course some of my other machines using the network. We have friends with three or four kids, which would have magnified that demand.
Gigabit can support ~25 simulatenous Blu-Ray streams (and that's at the full 40Mbit).
It wasn't all that long ago (~10 years) when the company I worked for had only 200Mbit to the internet, and that supported ~300 people pretty comfortably.
