Jackassavant
A person who’s so full of themselves they think they’re a savant, but they’re really just a jackass who got lucky.
"I got a perfect score. I didn’t cheat. I just got lucky.", @jackassavant303
"He’s not a genius. He’s just a jackass with a lucky charm.", Classmate
"He’s like a smart person who thinks he’s the king of the world.", Friend