Index funds have regularly ...

Index funds have regularly produced rates of return exceeding those of active managers by close to 2 percentage points. Active management as a whole cannot achieve gross returns exceeding the market as a while and therefore they must, on average, underperform the indexes by the amount of these expense and transaction costs disadvantages.
 Burton Malkiel

Quotes from the same author

It's like giving up a belief in Santa Claus.
 Burton Malkiel
Index funds are... tax friendly, allowing investors to defer the realization of capital gains or avoid them completely if the shares are later bequeathed. To the extent that the long-run uptrend in stock prices continues, switching from security to security involves realizing capital gains that are subject to tax. Taxes are a crucially important financial consideration because the earlier realization of capital gains will substantially reduce net returns.
 Burton Malkiel