<prompt> Human: Whenever we find ourselves with extra money after paying required bills food, utilities, loan minimums, employer 401k matches, etc, we should each ask ourselves what am I going to do with this leftover money. Assuming you have remaining debt at XX or could put money away into some other investment stockstotal marketfunds, real estate, money market account, etc. At 0 interest rates, I think many of us would easily say, Ill save my money and put it into a money market or some other investment, but as that interest rate XX goes up, we are faced with a harder decision to answer, where am I getting the most bang for my buck?So my question boils down to this: what is the maximum interest rate you are willing to hold debt at and instead make investments and what investment would you make stocks, ETFs, real estate, money market, etc?  <response>: 4; below that Id rather invest in low-cost index funds. 