This works because almost all the US uses first-past-the-post elections for the Presidential general election. So you get outcomes like this:
Scenario 1:
Biden: 10 votes
Trump: 9 votes
Kennedy/Stein/West: 0 votes
Biden wins the state
Scenario 2:
Biden: 9 votes
Trump: 9 votes
Kennedy/Stein/West: 1 vote
Tied vote, decided by game of chance/lawsuit
Scenario 3:
Biden: 8 votes
Trump: 9 votes
Kennedy/Stein/West: 2 votes
Trump wins the state
This is why you see huge financial support from Republican billionaires for third party candidates who have no chance of winning.
That’s not entirely true. There is one proven left-leaning group that can be drawn in by MAGA talking points, and that’s the Antivax moms. During the height of the pandemic, QAnon influencers were pretty effective at getting the cruchy-granola-crystal-healing-antivax moms into Trump. The guys at the QAA Podcast covered it really well, but the indoctrination path was basically: The Vaccine is Bad-> The Pandemic is Fake/Overblown-> Face Masks Actually Help Child Traffickers ->You Know Who’s Fighting Traffickers?Trump! Anyway, if an Antivax message can get these folks to support Trump, it can get them to support RFK.