Voting for independent candidates is an extremey misguided mistake. That sounds great. But comes from a misunderstanding on how elections should and do work.

This is partially caused by the winner take all model that the election runs under. 48 out of 50 states give 100% of their electoral college votes to 1 candidate. So the only way for 3rd parties to matter is if they can win 50% of a state.

If an independent were to be a viable candidate this would more likely mean that one of the two main parties was falling away (see the wig party Lee Lincoln) and would not mean the us getting a multiparty system.

We could get rid of the winner take all model and make everything proportional. But if you think that trump winning without the popular vote was maddening now. Imagine 7 parties all running and the Party with 35% of the vote (cough Evangelicals cough) winning consistently

But! Because “spiking a tournament” always sounds cool. Third parties are also extremely disingenuous.
If they were really serious about their party being a contender they wouldnt start with the presidency. We’d see Green Party governors and senators.

Libertarian state governments and house caucuses first.
They would be focused on grass roots campaigns attempting to win in more local elections or state elections building a coilition to become a very really 3rd party option.

Instead every year they run a spoiler candidate in presidential races trying to steal votes (generally from Democrats)to spread a very specific message while a spot light is on due to the size of the POTUS Race.

their efforts are at best misguided attempts to use the voice given to any pres canidate to spread a message but more often they are ego trips or at worst intentional attempts to hurt the Democrat running helping conservatives(at a bare minimum this is happening unintentionally)

Many different factors caused trumps win.
Hillary focusing on Texas and Georgia VS the Midwest.
Millennials not voting.
White women voting for trump.
Bernie or bust
But Gary Johnson eating up all the never trumpers.
And Jill stein eating up the left never Hillary votes. Def-

Definitely is a reason for the last four years. And of all the reasons listed this is the one that had intentionality behind it. Both 3rd party candidates knew this was a possible real outcome and were aiming for it.

A good option for this is ranked voting. Maine does it now. Basically this allows a person to vote for Jill stein as a number 1 but then if it becomes obvious she is no longer viable. Your vote now counts as your second or third choice. https://en.m.wikipedia.org/wiki/Ranked_voting

TLDR:
The way the system works currently doesn’t make it possible for multiple parties to exist.
If 3rd parties really want to succeed they would start at grass roots levels outside of potus races.
Because they don’t 3rd parties are intentionally hurting people by running.