expression, noun
degree of foolishness; extent of stupidity
Used to comment on how foolish someone or something is, often in a self-deprecating or critical tone. The phrase is a noun-like expression.
自分の馬鹿さ加減に呆れてしまう。
I'm amazed at my own foolishness.
あの計画の馬鹿さ加減は言葉
The stupidity of that plan is beyond words.