The temptation to use low-interest money from mortgages, credit lines and 401(k) plans to invest in stocks is great. : In a 1991 speech at the University of Notre Dame, Warren Buffett offered a few of what are now regarded as some of his wisest words: "I've seen more people fail because of liquor and leverage — leverage being borrowed money." The Berkshire Hathaway CEO told the campus audience they could make a lot of money without other people's money if they were smart.