IME it's rarely (if ever) pushback from incumbents that kills a small ISP. Generally it's all the same kinds of things that any other business struggles with - making your product something people actually want, letting people know it's available, finding the right employees, etc.

Local regulatory barriers exist and if you aren't persistent you can't overcome them. There were many times where I wondered if it was a bad idea or .. what am I doing here.

Being a telephone company made it easier to permit and working with the groups to permit it became possible.