I could have titled this post “Sometimes, he gets so fed up at stupidity that he draws a diagram,” but that’s too long and awkward.
Alliteration is not figurative language. Alliteration is a literary device, and figurative language is a subcategory of literary devices, but that does not mean alliteration is figurative language.
Here, have a Venn diagram:
Sarcasm is figurative. Hyperbole, simile, and metaphor are figurative. Repeating certain sounds in a string of words… Not figurative. (Repetition of words is also a literary device, but — you guessed it — not figurative.)