Sorry but this is just incorrect on many fronts. I can speak to this issue as a former engineer on Google Fiber so I got to see just how the sausage was made.
Existing national ISPs just have inbuilt advantages that a newcomer cannot replicate or can't replicate cheaply. This is the result of decades of lobbying state and local governments.
Take something as simple as where you run cables in the streets. You basically have two choices: you dig trenches or you string up cables on a pole. There is no best answer here as it depends on a lot of factors like weather and climate, local soil conditions, natural disaster risks (eg wildfires, earthquakes), distances involved and existing infrastructure and legislation.
So imagine in a given area trenching is uneconomical. This could be just because there's a lot of limestone rock in the soil so it's difficult, slow and expensive to actually dig the trenches and this may be complicated by local noise ordinances, permitting, surveying, existing trenches and so on. So you end up stringing up cables on poles.
Who owns those poles? Is it the city? Is it AT&T? You may have rights to string up cables on those poles but the devil really is in the details. You might have to apply for a permit for each and every pole separately. They might be approved by the city but then how does the work happen? Can you do it? Maybe. But you might need AT&T (or whoever) to do something first like move their own cables. Maybe several other companies have to move cables first. Maybe each company has 90 days to do that work and this can add up so it can take over a year just to be able to put a cable up on a pole. And you can't really do any work until all the poles are available. That's just how fiber works.
And where do you run the fiber too? Do you run it back possibly several miles to a POP? There are advantages in that but obvious disadvantages like cost and just overall cable size and weight. Or do you use local substations? If so, what kind of building is that? Is it a large building that residents find "ugly" and object to on aesthetic grounds or maybe even environmental grounds that means more delays? How much does that cost? Is AT&T grandfathered in with their substations and nodes?
And then after you've done all that and you have your last mile fiber, how many customers do you get? Roughly 30-40% of houses get fiber by how many companies are you splitting that pool with? You have to amortize your entire network build over your projected customer base and it makes a massive difference if it's 10% of dwellings or 15% or 30% or 40%.
In industry parlance this is called an "overbuild" and is inherently economically inefficient. It'll actually raise the cost of every ISP because each will get a lower overall take up rate.
That's why the best solution is municipal broadband that either provides service or acts as a wholesaler to virtual ISPs.
The cost of running a fiber cable from a POP to a house has only gone up over th eyears and it's the majority of your cost. That's really why Internet costs haven't come down. And also why the best Internet in the US is municipal broadband and it isn't even close.