<prompt> Human: So I know all the arguments for index funds and low expense ratios, but considering a fund outperforms the index, does it justify the higher expense ratio? So after deducting the expense, it still gives more than the index. What do youll think? Assistant: How consistent is the 10-20? Over how many years and how is it comparing to the SP?Human: Fairly consistent, never below, 8  <response>: Youre falling for survivor bias. Obviously with the number of people and funds that are investing at at time, some of them are bound to outperform. There is NO guarantee that this will continue. Bill Miller ran a fund that outperformed the SP 500 for 15 years in a row. The lost more than half of its profits the 3 years following that 15-year stretch putting it far below the SPs profits over those 18 years. Future performance is something which is very hard to predict so its hard to control. Fees is something you can predict. Dont do it. 