<prompt> Human: If the bank charges a 6 interest, and the index averages 10, youd be able to keep doing this and have money leftover. I am probably being stupid, and Id like you to tell me why.  <response>: This is what we call leverage. Its not crazy, it just heavily increases the risk involved.The averages are long-term over 50 years. For say the SP500, its very volatile and some years its up 20 percent and other years its down 20 percent. If you cant afford to pay the loan in the down years, youre screwed 