incomepetence
An inability to knowledgeably/effectively/responsibly manage earned assets, plan and maintain a budget, save/invest for the future, etc.
Due to his whiny-a** "affluenza" issues, Ethan Couch showed gross financial incomepetence by squandering money, misbehaving in catastrophically-irresponsible ways which resulted in voluminous legal-expenses for his parents, etc.