You're lucky. I only have Cable and (crappy) DSL. My cable is good, but the DSL is so awful that if my cable provider decided to triple their rates I would have no choice but to acquiesce and pay up. I think that's the very definition of a natural monopoly.
There is nothing that physically prevents you from building three separate water networks, it's just a stupid idea because it costs three times as much for the same result. And so it is with internet.
I know because I have three high speed ISP options at home: cable, fiber and (decent) DSL.
Where I live there is either cable (which exists because of cable TV) and terrible DSL (which exists because of phone lines). There has never been any attempt to wire the area only to provide internet service. And as far as I know, there is only one set of wires for cable TV. So, it sure appears to be a natural monopoly to me.
You're lucky. I only have Cable and (crappy) DSL. My cable is good, but the DSL is so awful that if my cable provider decided to triple their rates I would have no choice but to acquiesce and pay up. I think that's the very definition of a natural monopoly.
A very large number of Americans have no, or only one high speed internet provider - and that was by the 2010 standard of "high speed": http://broadbandnow.com/report/2013-underserved/
( Relevant YC discussion here: https://news.ycombinator.com/item?id=9044719 )