Look at the choices of candidates we've had....not a dime's worth of difference.
Whose fault is that. There will only be 2 choices, and people can’t be bothered beyond that. The best any 3rd party candidate did was Perot. The late night comedians laughed him away for the “2” parties. And the people ate it all up, he did have funny ears.
Any 3rd party that tries to start is piled on by the 2 gorillas, which are really on the same team. In the end most the population will do what the TV tells them to during halftime.