So, let me make sure I understand this..
If I vote for my candidate and my guy wins the primary and you don't like him and refuse to vote for him, I am at fault for losing the general election?
So, all I have to do is vote for who you tell me to?
That is a very funny definition of democracy...
If the choices for dessert are ice cream, cake, and cod liver oil, is it any surprise that nobody else will eat dessert if you made the only option cod liver oil?
If you present people with an unpalatable choice when there are better choices out there, objectively better choices, then yes, you are at fault.
If you make Trump your champion, then you own all the consequences, including those arising from the fact that you refused to listen to anyone who disagreed with you.
That's the danger of echo chambers and the problem with primaries is its too easy for them to become echo chambers dominated by a small group of very noisy partisans who are in fact a very small minority of the general voting population.
Outside the echo chambers of the primaries Trump is increasingly being rejected by the very people whose votes he will need in the general election. Cutting off your nose to spite your face is never wise policy.