You'll notice that in every one of your possible outcomes there's zero chance of C ever winning. That's the reality. When it comes to presidential elections, voting for C means you throw away your chance to vote for someone who actually has a chance to win.
In theory, if massive numbers of people all voted for C then C could get more votes than A or B, but the odds of that happening are so low that it's never once happened in the entire history of the nation. The incredibly low odds of winning millions in the lottery (something that routinely happens in the US) are much better than electing a third party candidate (something that has never happened in the US).
Since only A or B ever have a chance to win, your choice is limited to only A or B if you want to have any meaningful impact on the outcome, and because of that fact your choice becomes binary: Either meaningfully participate in the election (by voting for A or B), or don't meaningfully participate in the election at all (either by not voting or by voting for C).
The system could be fixed to give C a chance at winning, but that would require the same people who benefit from our two party system to support fixing it and not many are eager to hurt their own (or their own party's) odds of getting elected.
In theory, if massive numbers of people all voted for C then C could get more votes than A or B, but the odds of that happening are so low that it's never once happened in the entire history of the nation. The incredibly low odds of winning millions in the lottery (something that routinely happens in the US) are much better than electing a third party candidate (something that has never happened in the US).
Since only A or B ever have a chance to win, your choice is limited to only A or B if you want to have any meaningful impact on the outcome, and because of that fact your choice becomes binary: Either meaningfully participate in the election (by voting for A or B), or don't meaningfully participate in the election at all (either by not voting or by voting for C).
The system could be fixed to give C a chance at winning, but that would require the same people who benefit from our two party system to support fixing it and not many are eager to hurt their own (or their own party's) odds of getting elected.