Because if you can pick an index fund with low fees, you are already beating most professional stock pickers. Yes, you may find the one or a few active investors who are amazing, but unlike law or medicine, there is a fallback option that is consistently successful in both short and long term compared to most stock picking, even professional. Note that you may all lose if the market goes against you, even active stock folks with lots of "hedges against the downside" and whatnot.