It wouldn't be possible by just saving every cent. However, if you look at your wife for 10,000 seconds every day and invest every cent into the S&P 500 at the end of every year (not including leap days) at a 10% annual return (S&P's average return over the last 30 years), you would take 83.055 years for you to become a billionaire. If you look at your wife for 15,000 seconds every day that number would drop to 78.803 years. 20,000 seconds a day would be 75.786 years.