You’re saying things, but you’re not explaining them. Historically third parties in the USA have had major influence on policy.
I am not American, but let me ask you one thing, is it worth it to take your stand in this election to rest your case in the fact that your vest stays clean - even if this is the last vote that you get?
Because what I can see is that that’s precisely what happened in the Weimar years. People could not fully identify with one party so they made their own slightly different one. The only ones however to rarely actually care about policies are the fascists/nazis/right-wingers