The path to a viable third party presidential candidate has to pass through the down ballot races. If you want (for example) a future green party or libertarian president, you need a bunch of governors, senators, and representatives first.
Third parties struggle to get on presidential ballots because they are ineffectual on a national scale. They’re ineffective on a national scale because they barely exist in between presidential elections.
Expecting to change the political landscape from the top down is misguided and unrealistic.
Molly White - https://www.citationneeded.news