There is a lot of ideology involved, which correlates rather poorly with intelligence. There are, for example, quite a few Republican politicians that aren't obviously stupid, who still spent decades denying first the existence of climate change, then the human contribution, followed by the risks and, finally, our ability to act against it.
Other example: when people say "Barack Obama was not born in the United States" it is not intended as a statement of fact, which is why no amount of fact-checking and birth-certificate-producing stopped people from engaging in that particular conspiracy theory. It is an expression of ideology.
And because every comment on such topic must end with George Orwell: In 1984 the highest achievement of ideology is the expression of facts that are obviously wrong.
It’s a veiled way of signaling they are willing to discriminate against certain races to other racists, while claiming plausible deniability.
But there are two conclusions you might draw from that: (A) that intelligence and education aren't helpful, or (B) that those making horrible decisions were being selfish.
Given the trumpian sentiment of "not paying my taxes makes me smart", and perhaps the fact that other people were even smart enough not to say something like that (but still to act on the idea), I'm thinking you need to consider (B) as a serious component here.
That would suggest that intelligence and education might still be useful - but only when dishonesty and selfishness is not a dominating risk. I suppose there are measures one might take to at least reduce those risks, since obviously completely eradicating those is unrealistic.
For instance, if the educated are good at serving themselves but pullign the wool over the electorate's eyes, then perhaps more audits would help. A culture of much harsher penalties for selfish leaders, even where the selfishness isn't illegal, might help. But perhaps also the electorate itself should be smarter too - and that's not entirely impossible in principle too; e.g. you could imagine a pyramid scheme of elections, not too different from the electoral college today - just with more levels (not just two), and with explicit decoupling of the elector from their vote (so no more "republican" electors or "democrat" electors - they too are free agents), and with the explicit aim of voting for people who you think you can most trust - intellectually, morally, and as a planner - instead of those you most agree with (since with multiple levels, that's kind of hopeless anyhow).
...So I'm not really serious with that last suggestion, but I do think we need to be exploring options. A disillusioned electorate mixed with manipulative, egotistical, untrustworthy politicians, spiced with lavish lobbying, no funding transparency, and media so full of noise the signal is hard to find - that's a recipe for serious food poisoning. It may seriously simply help to switch electoral systems every once and a while, even if there's no single best system - simply to shake loose the manipulative habits that settle in after a while.
I'm sure this would work out horribly.