They suffer from incuriosity and arrogance. They read 1/4 of a book about something once and now believe that entitles them to an intransigent opinion on a topic they absolutely don't understand at all. Not only does it entitle them, that's the only thing they're going to spend their time on: sharing and defending their wrong opinion, to the death.

At a fundamental level this is a learned behavior for what counts as discourse and it's one that ties one's own sense of identity and value to "having and sharing opinions" even when unearned. You will find this behavior among most people in the United States. Commies tend to be one exception because they have to read a lot to validly claim that name and because they can't simply absorb their opinions from the mainstream lib sources that, say, radlibs do, and must instead critically engage with media in order to maintain their positions.

The only solution is humility and education. Humility usually comes from something shaking up their worldview. Something personal or dramatic. Rarely from nicely talking to them in the marketplace of ideas. Sometimes from good dunks.