In To Kill A Mockingbird, there are many examples of Bob Ewell being imprudent. He lacks wisdom. He is rash and ignorant in his actions. As the head of his family, he is a disgrace. He is a drunkard. He spends all of his relief money (welfare) on alcohol. He beats his children and possibly even sexually assaults Mayella:
He is unable to keep a job, spends all his relief money on alcohol, and traps animals outside of hunting season. He provides little support to his large, motherless family, and is reputed to beat his children (and perhaps sexually abuse them too, as Mayella's testimony hints).
Bob Ewell is despised by the community. He is considered white trash. He has no morals. He is a liar. He accuses Tom Robinson of sexually assaulting his daughter Mayella. In reality, Bob Ewell is the guilty one. He is definitely imprudent.
Bob Ewell spits in Atticus Finch's face. He is rude and violent. He has no human decency:
I wish Bob Ewell wouldn't chew tobacco," was all Atticus said about it.
In the end, Bob Ewell attacks Jem and Scout. He did so unwisely. Bob had no idea that Boo Radley would come to the children's defense. Bob Ewell loses his life because of his lack of self control. He has no insight. He is dangerous. He dies because he attacked Jem and Scout. Boo Radley kills him with his own knife.