If it was easy to do with a lot of margin it would have been done by someone else in the private sector. In fact, they tricked these companies into making investments that weren't worthwhile for them. Sounds like the kind of people the deserve the shitty internet they have.
The problem is all the regulatory stuff that means the bigger you are and the longer you've operated for the better you understand and have relationships with the often pretty inept regulatory bodies that can stop you.
This is a fundamental problem of value creation and value extraction. Just because the ISP's can't extract the value of adding the additional fiber capacity doesn't mean it doesn't confer that value to the customers. We live in an age of value extraction, what's colloquially known as "enshittification", that can't go on forever. Somebody has to create the value that is being extracted.
It's the old Marx quote: "From each according to his ability, to each according to his need". Except you know, the opposite.
That’s not necessarily true. A lot of companies are very risk averse and will sit there creaming off profit and not making any investment.
If someone came to you and said - you have two choices:
Work incredibly hard, raise a lot of money, build a bunch of infrastructure. And at some point in the future you will make some more money.
Or - keep taking your very nice high guaranteed salary for the foreseeable future.
What would you pick?