I have. (IT has a perhaps not surprising amount of them). Usually at that point it isn’t stupidity, it’s a form of selfishness. Either they prioritize what they need and either don’t see or don’t care the harm (some small business owners) or they have a strong belief that they are right, and won’t acknowledge any other viewpoint. They can do good work in stuff they know, but may be insufferable if you’re trying to correct their way of doing things and they just think their way is better (our whole section of IT lost access to edit firewalls because one of our higher placed techs kept doing things his way and security kept having to fix it. I replaced him when he left). People who are skilled in one area also seem to think they’re automatically smart in others, like Ben Carson.
Back to the small business owners, Behind the Bastards has a couple of episodes starting with How Nice, Normal People made the Holocaust Possible. In it he discussed how many small business owners feared becoming destitute, and in that fear despite not needing the help fell for fascism in order to keep their place. I’ve met people who said they voted for Trump because they thought he’d be better for them as a business owner, and there was pressure from business owners during the pandemic too. These people aren’t necessarily idiots, but their priorities put themselves before the other.