You've covered the "last mile", but there is the upstream world to take into consideration.
1) Connecting into a CO is one thing, but your fiber is going to need to connect into something. Who is paying for your optics, is there a port or line card that can accept those optics? Does the CO actually have enough bandwidth upstream? This is a real issue.
Back in the 90s, I helped set up an ISP in Boston proper and our main competition had well over a 1000 customers attached to a single T1 (1.5mb/s) link. Everyone wanted 28.8k speeds (lol), but would normally get ~300 to 2400bps. The competition had a bunch of modems with a single upstream link. No one wanted what we were selling - guaranteed bandwidth / true 28.8 bandwidth all the time. People wanted $19.99/unlimited all you can eat. People still want that today.
Back to the CO, maybe you are lucky and they have some open ports. Worst case scenario, they want you to plop down a router and you'll do 10gb/e between. You can go with a homemade box and hope that it is stable, or you can buy expensive network gear.
2) To your customers, that "CO" is the "internet", but to that vendor/telco, it is just a single point of presence (POP). That CO has to connect to other POPs that are owned by them, and that costs real money. Eventually through a unknown number of hops, your traffic will hit an exchange point or carrier hotel. This is where your traffic exits their network and is taken up by another provider and/or company (google has their own fiber plan, for example). The amount of bandwidth at these peering/access points is finite and providers choose to peer with each other, usually at no charge, if there is an equitable distribution of traffic. The last thing that you want is for one company to take up all of the (finite) bandwidth at a peering point.
An ISP connects to multiple carriers (l3, cogent, comcast, att,verizon, etc) so that your customers have quick access to the websites/services that they want to visit - which most likely have to traverse one of those other providers. Similarly, their customers will want to access services that you are hosting, so you will take in a similar amount of ingress traffic.
With the fiber network that you are connecting your customers to, they'll most likely want to access bandwidth intensive services. You better hope that your CO has upstream capacity and a fast path to netflix/hulu/facebook/google/akamai/etc.
Or you, as a internet service provider, try and peer directly with the content providers if they allow it. If there are only 2-3 hops between you and Netflix, your users will love you. If they have to bounce around the country a couple of times, your customers will go back to Comcast (because they have a well connected backbone).
3) This doesn't even cover where you are going to get your IP addresses, if your upstream provider will announce them in BGP for you, etc. Or maybe you connect in to two carriers, get an ASN and announce your networks yourself. You are still at the mercy of your upstream providers.
I think a lot of these details are often overlooked when someone talks about network neutrality. I think network neutrality is a glib term for a number of issues:
- filtering of traffic and/or inability to access a service
- loss of freedom to host stuff "for free" on the internet
- lack of competition in "the last mile".
The FCC/TitleII stuff, from what I've heard, negatively impacted small WISPs that were trying to start up, by assuming that they were the same size as major wireless providers. A $20k fine because your lawyer failed to properly submit paperwork can wipe you out if you are a simple provider that is trying to provide access to a small community. You aren't AT&T, but title II will assume that you are - and penalize you accordingly.
For more information, read some of these filings/papers:
https://ecfsapi.fcc.gov/file/10717113433056/FCC-17-108%20Res...
and in particular:
http://www.interisle.net/sub/FCC-14-28%20NN%20Interisle%20Co...
-Paul