I've met some very, very insecure extroverts. They'll crack jokes all day and make a lot of noise, then go home and are desperate for company to distract themselves from their own ideas. Met some very confident extroverts, too.

Also met some insecure introverts, people who had social anxiety. Also met some very confident introverts who will go out, shake hands and converse, then spend hours alone going over what they learned while they were out.