i’d love to pay 10 percent of my bill for 10 percent
That's not how it works, you generally pay 20% less for half the speed. Because speed is not the main price factor anymore. The logistics and cabling are.
I we didn't have 500 Mbit and above, you'd probably have to pay the same for 100 Mbit as we do for 1 Gbit today.
The price is in the cabling, maintenance and support. And none of those change much from having higher speeds.