Ultracrepidarian

Do you know any ultracrepidarians? And, no, such people are not members of some obscure cult.
 
In brief, an ultracrepidarian is a presumptuous person who has no special knowledge of a subject but who expresses strong opinions or advice about it anyway.
 
Here’s the origin story: A famous painter named Apelles lived in ancient Greece. One day a shoemaker pointed out a defect in Apelles’ depiction of a sandal in a painting. Apelles duly corrected the mistake. Emboldened, the shoemaker began to point out other defects in the painting not related to sandals. Apelles cuttingly replied that the shoemaker should not make judgments ‘beyond the sandal’; i.e., stick to what you know—sandals.
 
The ancient Greek word for sandal was krepis; in Latin crepida. The Latin phrase ultra crepidam literally means ‘beyond the sandal’. However, over time, ultra crepidam became an expression meaning ‘don’t make judgments about something that you don’t know anything about.’
 
Image:
A 5th century BCE Athenian shoemaker cuts a piece of leather round the foot of customer.
Image: Ashmolean Museum, Oxford. Athenian black-figure pottery pelike, 5th century BC
https://commons.wikimedia.org/wiki/File:Athenian_black-figure_pelike,_5th_c_BC,_shoemaker,_AshmoleanM,_AN_1986-1908_G.247,_142573.jpg
 
Reference: Online Etymological Dictionary, https://www.etymonline.com/
https://www.merriam-webster.com/words-at-play/polite-words-for-impolite-people/ultracrepidarian
https://en.wikipedia.org/wiki/Sutor,_ne_ultra_crepidam