Sit in your place, and none can make you rise (Old English Proverb).
Oh how the mighty have fallen. 2 Kingdoms 1:25 Orthodox Study Bible
Every cock is proud on his own dunghill. (Dictionary of English Proverbs/Thomas Preston)
“She thinks she understands the world just because she’s read a bunch of books.” Susan Rebecca White, A Place at the Table
“Arrogant people habitually overestimated their own abilities and underestimated everyone else’s.” David Baldacci, Absolute Power