From a usenet posting little less than a decade ago¹, something that explains a common pattern in “high-level flame wars” on the internet …

I think the term you’re looking for is “willfully ignorant” or perhaps “stubbornly ignorant”. They’re actually too fundamentally intelligent to be truly stupid, but the intelligence is being perverted in the service of an active ignorance that seeks reinforcement of its own preconceptions, rather than being open to the subtle panic that inevitably arises when learning something truly new & different.