"I wouldn't support this party unless it had more support"
american third parties are all pretty stuff but it's a self-fulfilling prophecy if you don't support them just because they aren't popular
The thing is, if you look at elections through the lens of game theory, it is impossible to have more than two parties in the long run when you use first-past-the-post voting systems. Let's look at the approximate percentages of votes cast for each candidate:
(3rd party percentages estimated based on a couple states:)
Clinton (D): 48%
Annoying Orange (R): 47%
Johnson (L): 3%
Stein (G): 1%
Let's say that Stein gets a massive increase in popularity from 2016 to 2020 because Annoying Orange got rid of the EPA and a chemical plant blew up and gassed a bunch of preschoolers. The vote in 2020 could look like this:
Annoying Orange (R): 34%
Sanders (D): 31%
Stein (G): 30%
Johnson (L): 5%
Note that 2/3rds of America did not vote for Annoying Orange, but he wins a second term. What happens then is that the Sanders and the Stein folks, who both hold the same positions on 99% of issues, realize that they screwed themselves by existing as separate parties. So their party officials meet in a basement somewhere and decide to merge and form the Democratic-Green party. Likewise, a substantial number of Johnson's voters rally under Republican conservatism in order to counteract the new liberal alliance. Then, with forces joined together, they successfully rally a majority of voters and sweep the 2024 election.
Kanye (D-G): 61%
Pence (R): 39%
So unless we can boil politics down to three or more factions with absolutely irreconcilable differences, the two losers are always going to trade and merge voters in order to have a better shot at winning. And although the Libertarian and Green party do have their own distinct beliefs, they are also both very close to the Republican and Democratic parties on general issues, respectively.
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