As long as people keep thinking like that, it will be a self-fulfilling prophecy.
When a 3rd party gets the majority control of one state legislative chamber through even a coalition, I'll start listening. One 1/2 of one chamber. About 45 state rep sets here and 16 state senate senate seats could do it here. That's it. Until that happens, 3rd parties are a protest vote and I'm wasting my time, money and effort unless I do protest vote, which I have done in the past.
Teddy Roosevelt as an ex-president lost his 3rd party run. So did governors like George Wallace and Strom Thurmond. So did billionaires like Ross Perot, not to mention Nader, Bob Barr, and Pat Buchanan. Outside of Roosevelt, Wallace, and Thurmond, they won nothing. Most don't get 2%.