If they're literally charging double compared to the domestic competition, it's pretty outrageous.
Google Fi is also flexible in that you don't have to spend $80 a month if you are using less. When I don't have to do a bunch of tethering for work, I usually spend $30 - $40 a month total.
Thus Google Fi cheaper for a variety of use cases. Different plans/carriers are cheaper for different use cases. Just because a carrier other than Google Fi is cheaper for your use case doesn't make Google Fi outrageously expensive.
Basically it caps off at $60 after 6GB, is free up to 15GB, and then throttles.
That's pretty great pricing especially considering it works anywhere in the world.
Disclaimer: I am a Google employee, Fi customer outside of work, don't work on Fi.
I guess when I signed up for Fi I imagined myself travelling more outside of North America.