When people have that kind of money, it isn’t stored as cash in a safe somewhere. It is in the form of things like real estate and business holdings. And exactly how much money any given person is worth depends upon what other people think those holdings are worth. And those valuations can change by the day, hour, or even minute.
Sometimes it isn’t a matter of simply losing everything. Seán Quinn, for example, was the richest man in Ireland at the start of 2008 — estimated to be worth $6 billion. Although he started off in the 1970s selling gravel, he built a business empire that spanned construction, real estate, and insurance. But when the financial crisis hit, his business empire crumbled. Not only did he lose the $6 billion he was thought to be worth, he ended up over $3 billion in debt before declaring bankruptcy.