Why aren't there more news stations?

I don't understand why the mainstream media is pushing so hard for their own agenda.

I also don't understand why those, who are not getting their agendas out to the public, don't just start their own radio and news channels.

Why is there only a two-party system being pushed?

If channels like CBS, NBC, ABC, etc., are allowed to exist and push their agendas on Americans, but no one else can have alternative stations, it makes me wonder who is controling the existing news network, and why don't they want Americans to know about other candidates and other issues?

Isn't that a monopoloy, and/or dictatorship where the media is filtered for the common person, as if we don't have a right to think, act, or speak beyond what the major networks want us to?

Trying not to be shark bait.