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.
So far the polls don’t show that kind of backfire. Would take a bunch more people hearing about why he’s actually running to create it.
Republicans have done this for decades to great success. Usually they’ll push a wedge-driving issue with online operatives sometimes posing as grandstanding leftists who will vote 3rd party, independent, etc.
It rarely works for Dems, but Libertarians did screw over Trump to some extent last election thanks to Jojo
“Shit, Rita, that’s what we’re getting paid to do, not what we’re getting paid to say!”