Investors around the world are flocking to passively managed funds. They do not trust that active funds -- that is, stock-pickers -- can get them better returns, especially after fees are accounted for.The arguments for passive investing have been well-documented, and these investors are smart to listen to them. After all, even Warren Buffett promotes passive investing in low-cost index funds (perhaps the ultimate example of "do as I say, not as I do" in the investing world).From 2009 to today, passive investing's share of assets under management in U.S.