Where does the leverage lie with breaking down ISP monopolies? Is it a product of regulation at the municipal level, or state laws, or federal regulations? It

Where does the leverage lie with breaking down ISP monopolies? Is it a product of regulation at the municipal level, or state laws, or federal regulations? It doesn't seem like a situation that's going to be improved by consumers complaining about the ISPs. For example, Comcast is consistently derided for poor service and has ranked as one of the most unpopular brands in the US as early as 2010. Is there even a prospect of competition if the regulatory picture changed, or is it just too capital-intensive to roll out new infrastructure and bring a competing service to market?