Index funds beat most active managers — including professionals

In 1976, John Bogle launched the first index fund available to ordinary investors at Vanguard, tracking the S&P 500. Wall Street derided it as 'Bogle's Folly'. Over the following decades, data consistently showed that after fees, roughly 80-90% of actively managed funds underperform their benchmark index over a 20-year period. Buffett famously wagered $1 million that an index fund would beat a portfolio of hedge funds over ten years — and won comfortably in 2017.

Source: Bogle, The Little Book of Common Sense Investing (2007)