Even in subjects they clearly weren't familiar with, they would speak as though they were experts on everything with little more than their egos to back it up.

I'm sure there's a term for it, but after becoming aware of this effect I find myself impressed at how often "smart" people would rather talk out of their ass than admit they don't know something.

Anecdotally the other day one such friend was saying something about how armor in medieval Europe was superior to all other forms of combat at the time.

I said I thought the Mongols tore up Europeans despite not really wearing armor. He told me that was ridiculous because the Mongols had never fought medieval European forces.

Having the Internet I pulled up an article on the Mongol invasion of Europe and he said oh yeah of course but they didn't make it all the way to Europe. Then I pointed out the article mentions they invaded Poland and he said well they didn't fare very well there.

I gave up at that because it was painfully clear he was speaking authoritatively about a topic he had only a vague understanding of.