Or they could use that 97% profit margin they pocket to upgrade their infrastructure. Google on the other hand is showing that it can implement fiber optic cabling capable of gigabit connections for only dollars more than what people are paying for their shitty old copper wire cabling that current ISPs are using and refuse to upgrade from.
As long as ISPs and local municipalities remain intertwined together, you're not going to see much upgrading. Google has only gotten as far as they have because city leaders see more $$$ from Google rolling out their fiber.