This is a textbook lesson in how one person, who really doesn't think their one & only password they use for everything, could possibly result in catastrophe for so many people.
www.tomshardware.com

158-year-old company forced to close after ransomware attack precipitated by a single guessed password — 700 jobs lost after hackers demand unpayable sum
An employee’s weak password was the company’s Achilles' heel.