Oblivious douchebag
A person who’s so clueless they think everyone else is stupid, but it's just them being a complete waste of oxygen.
Thought he was the most popular kid in school, then no one showed up to his party.
Told me he was going to be a billionaire, then spent all his money on a pizza.
Argued with the teacher for 10 minutes about why the sky was blue, and no one cared.