Ultracrepidarian [uhl-truh-krehp-ih-DAYR-ee-uhn] (n.) One who gives opinions and advice on matters that they know little or nothing about. (adj.) Pertaining to one who is talking about things beyond their scope of knowledge.

Used in a sentence: “Few things are as veritably vexing as the uncouth utterances of an ultracrepidarian - a consummate cacafuego of confidently clueless commentary!"

This applies to 99% of the population. Maybe 100%.

ohoho there's no shortage of these in today's world...