> The cost of the decade-long project to design, build, and deploy the constellation was estimated by SpaceX in May 2018 to be at least US$10 billion. [https://en.wikipedia.org/wiki/Starlink]
Which would be 1/8th the cost you describe (though probably more by now, I haven't found any figures yet). It also covers a larger geographic area (and therefore a larger number of people) in a shorter time than any cell tower + cable solution would, short of conscripting every possible technician in the US to accomplish the effort.
Starlink also gets to piggyback on other SpaceX launches so they aren't eating the entire launch cost themselves, it's subsidized (or can be) by their other customers. This is what I'm talking about when I say that presently it's more economically viable. It sucks about your situation (being so close to gigabit Internet without access), I've been there, too. Cable companies and ISPs in the US suck.
EDIT:
https://www.ft.com/content/4f992537-59f6-4d09-b977-c33945dba...
More recent, June 2021. Musk is expecting to spend $30 billion to cover 12 countries, and expects to have spent $10 billion before becoming cashflow positive with Starlink.
EDIT: Fixed link above, not sure why I ended up with a link to a subheading.