We’re on 1 Gbps plan with AT&T and we’re never coming close to using it all.
For starters, most WAN devices cannot use the full bandwidth anyway. And even streaming 4K w/ HDR takes only about 25 Mbps (on Netflix). Even if all your users were watching different streams at the same time and you had a lot of devices connected that used up some extra bandwidth, it’s hard to see the need for 2 Gbps for most non-server applications.
Maybe if someone was torrenting a lot they could use a lot since fiber adds download and upload bandwidth and there’s really no limitation on either if you don’t set limits. But that doesn’t seem like a very common use to me to justify the extra cost.