Why have minor parties been so unsuccessful? Well there are many reasons, including their parties way to young, our political system, and lastly different ideologies of the parties cause them to be unsuccessful as well.
So to begin with, these minor parties are way too young. The Democratic and Republican party has been here for at least 200 years. And in those 200 or so years, they have continually showed ideologies that have been consistent, as well as reliable (to an extent). The minor parties can’t complete with this, because these minor parties are relatively new, and haven’t quite proved themselves to us yet.
Second reason why minor parties have been unsuccessful is because our political system. Our elections have a winner-takes-all system. Making this really bad for minor parties because they simply do not get enough votes, when you think about voting for a minor party, the thought of your vote becoming wasted is enough to change your vote to a major party. These votes are wasted, because only one person wins, not two or three, making the vote more powerful. No one likes to think their vote is wasted, right? Say if the system was more like a proportional representation, like in the Netherlands, then it might be enough to get the minor parties some seats in the house. Which then could allow the minor parties to show what they are made up, and run with the big boys, who know? (just a thought)
Finally the last reason why the minor parties have been unsuccessful in elections is because of the minor parties ideologies. There are so many minor parties, and each one with a different ideology. Makes it difficult to narrow it down to one, and as well has finding one that matches the ideology you like.