I broadly agree with you that everyone who voted for Trump was in some sense wrong, but I don’t think your framing is helpful. Even honest people with good motivations make mistakes and I think that some percentage of Trump voters was essentially mistaken when they voted for Trump (and if they’re planning to vote for him again).

Specifically, the mistake they’re making is believing that the ends justify the means.

Let’s say a person holds some sort of conservative belief that’s not in itself evil, like that taxes should generally be as low as possible, that any fiscal headroom should primarily be taken as an opportunity for a tax cut rather than for more state spending. There’s nothing wrong per se with believing this (all tax policy is a matter of balance and there will always be some people who, on balance, think taxes should be lower). However, believing that this is so important that you should vote for a person like Trump is wrong: the ends (low taxes) don’t justify the means (Trump regaining the presidency).

NB: The question as to whether low taxes are actually good, or of whether Trump will actually deliver them, is irrelevant to this argument; the whole point I’m making is that these people are mistaken, so if they’re also mistaken about the merits of low taxes that’s a point in favour of my argument, not against it. For what it’s worth, Trump will raise taxes on all Americans because his tariff scheme is a tax that will be paid for by Americans.