This is just disgusting, fatcat stuff. I don't know what kind of a business plan they have, but it seems to me that they are trying to transfer the financial burden of the whole investment to the customer, all in the first month. After that it's just $280 profit/month/customer.
In Romania the main Gigabit Fiber provider is still paying off the loans they took out for the fiber infrastructure, about 10 years ago ... back then they offered just 6Mbps speed, but it was already on fiber (FTTB), the phone line too, at a competitive price, just ~$12/month and no installation fee, if you signed a 2 year contract. They also upgraded your speed whenver the infrastructure was inproved, even though you still had 6-18 months on the crappy contract you previously signed.
What US providers don't understand, is that clients won't use their services non-stop at full speed. The large bandwidth is just assurance that live streams, on-line gaming and video chats won't be affected, no matter what. Nobody is going to download torrents at 120MB/s, 24/7. That would be ... 10terrabytes/day. Who/what can afford that much SSD/RAID storage?