Most people don't need 1 Gbps.
The only people who need 1 Gbps are institutions with servers or a lot of computers on the premises (such as a call center, hospital/medical center, or a high school).
For most residential users like myself, I only need the 50/10 plan through Comcast.
It is split between several computers, tablets, and gaming consoles.
For most residential users, 1 Gbps is overkill (like using a tractor trailer to bring home a week's worth of groceries).
You don't need it because you don't have it. Look beyond your feet! If we had 1Gbps service you would see remote cloud, family, or "group" LANs forming. Ie: I would swap hobby nature video files we all take (often around 1+ gig size) with many of my relatives and it would be as if they were connected to my local LAN. Right now my only option is to send them snail mail or compress them to crap quality. Just because monopolies don't allow it to exist doesn't mean people wouldn't find new life transforming ways to benefit from it. I'm sure when the first cars were offered many people said "No one ever NEEDS to go as fast as 20 mph!" "What a huge waste!"