Reusing passwords across multiple accounts is risky because it increases the chances of cybercriminals accessing sensitive information if any of your accounts are breached. Hackers could exploit personal details from less secure accounts like social media to access financial accounts protected by the same password. They could also more easily compromise business accounts by guessing recycled employee passwords obtained from data breaches. Additionally, password reuse makes people vulnerable to phishing attacks where hackers pretend to be legitimate websites to steal login credentials.