글 못한 놈 붓 고른다. A man who doesn’t know how to write, yet looks for a brush (to write with).

This proverb describes someone who attributes their inability to do something not on their own lack of talent but on the conditions around them. (자기의 재간이 모자라는 것은 생각하지 아니하고 객관적인 조건만 탓함을 비유적으로 이르는 말)