To people with bad internet, welcome to the svck. Know your pain is shared, I won't be playing Fallout 4 either, and that despite apologist propaganda, it is unnecessary suffering imposed on us out of greed. If you haven't bought Fallout 4 yet, my advise is don't, go play something else, wait a year, get the GotY edition with final patches (fewer bugs) and all DLC for half the price (or less), probably a much smaller download (if any), and tons of mods available. Yes, it svcks, its gamesas's fault, for a single-player offline game it cannot be the customer's fault, better companies don't do this to their customer's, drown your sorrow in some other games, and discourage others from getting this, or even any other games from gamesas.
My sob story: I was a long time gamesas customer, and fan, from Morrowind through Fallout 3, but they ended that with this broadband-only DRM abuse. I pre-ordered New Vegas via Amazon, my first indication it used Steam was the Steam installer, no mention of that anywhere, not on Amazon nor the previews and had trusted gamesas not to use that, but by then I couldn't return it (open box), and now years later I still can't play it. I watched Skyrim come and go, instead doing another huge mod build for Oblivion. For Fallout 4, with gamesas pissing on its customers yet again, I'll probably do another huge Fallout 3 mod build (next year).
I'm on 26.4kbps dialup, over 40+ year old noisy phone lines, because Frontier communications refuses to efficiently spend the money, hundreds of millions, the government gave them for infrastructure improvements. Instead they waste huge amounts of money on shareholder dividends, reducing prices, buying more land-lines from Verizon, advertising to increase market share in urban areas while they practically ignore the majority of their service area where they hold monopoly status, fending off class action lawsuits over failure to provide even basic DSL performance on higher end service plans, buying state legislators to prevent state action against them, and so on. Its obscene, should be criminal, and some of it might actually be, but there isn't a damn thing I can do about it.
Despite that, I downloaded over 5 gig last month, most of that was Oblivion mods, including Better Cities (~1.5GB, ~150 hours). The problem is Steam network overhead, for ads and social media features I don't use, causes downloads to fail, with FONV I let it run for ~6 weeks, it managed to get maybe 200MB. If gamesas used the physical media efficiently, instead of abusively wasting people's time and bandwidth, my 26.4kbps dialup would be fine.
Through it all, if gamesas re-released FONV (GotY), Skyrim (GotY), and Fallout 4 on DVD, ready-to-play, ideally only with disc-check DRM like FO3 (I'd even tolerate non-Steam online activation), I'd buy it in a second, despite the abuse and already having a useless FONV disc.