Such people have all but destroyed our world. Everything they touch turns to shit - we had one of these people as Chancellor of the Exchequer and he doomed another generation to low paid poverty with his clever-stupid little schemes that didn't work. Then he became prime minister and saved the world for himself, however this failed when it transpired that all that nasty stuff that was hitherto off the books very suddenly went on the books, and we were all fucked.
Before they fucked the economy though, the stupid people who think they're clever fucked the environment. One thing they did was to invent clever machines that, they promised, would generate infinite amounts of cheap, clean energy. They knew it was completely safe because they said it was, and, hey, they were really clever so if they said that nothing could go wrong, then obviously nothing CAN go wrong.
The result is that every 20 years or so a nuclear power station goes BANG near a populated area and several million people get their DNA rearranged free and gratis courtesy of the Friendly Atom. Plus, every ten years or so, some tin pot dictator gets himself a nice little pile of atom bombs to play with. Fun!
Having fucked over the economy AND the environment, the stupid people who think they're clever turned their eyes to everyday life. The problem with computers, which until then had been made by people who really WERE clever and not just narcissistic assholes who thought they were, was that they were too simple, too easy to use. Why, any person with sufficient training, could run a large and powerful server of their very own.
Oh dear, they said to themselves. We can't have that. So they invented their own operating system, one that didn't work properly and whose innards made no sense, and named themselves masters of their own domain. Everyone who knew what they were talking about told the stupid people who thought they were clever that they were just really fucking stupid, that nobody in their right mind would want to use an operating system that had barely changed since the '60s, and that people were better off with computers that were easy to use.
"Ah-ha", said the stupid people (who thought they were clever). "That's where you're wrong. You see, if we make it really hard for people to use computers again, then eventually the only people who can get jobs in the industry will be borderline autists like us. Incapable of relating to other people's needs, we'll just arrogantly tell the public that they're too stupid to use computers and that the problem here is simply that machines are always right and people are always wrong. We'll dress this up in clever language and as a result our closed shop will be protected forever."
And so they did. Computing became an obscurantist subject once more, impossible for anyone else to break into as the information on how to work them was spread across a billion web pages and thousands of doorstop-thick computer manuals that went out of date almost as soon as they rolled off the presses. People everywhere tried to learn how to use the new operating systems, which didn't work properly and could only be maintained by experts, but found that they couldn't because, far from being logical, their setup made no sense at all.
And so, stupid people who thought they were clever consolidated their grip on Earth. The economy was fucked forever - whoever was in charge, clever idiots would come out of the woodwork and force their moronic, expensive little schemes on the country with the result that the only people with money were a few oligarchs, politicians, and of course the clever idiots themselves. The environment was screwed, as the clever idiots conned people into accepting clever-stupid schemes for "capturing" and "offsetting" pollution rather than just making less of it, schemes which only ever worked on paper - and we were kind of running out of trees anyway.
And of course technology was constantly breaking down, because the operating systems they were based on were all designed by clever idiots who were so clever they could do really stupid things like write programs with no real operating manual, but at least the clever idiots had a job - fixing the stuff they'd fucked up in the first fucking place!