How do you assess investing in (non-index) mutual funds and ETFs? Presumably, the managers of these have access to all the data available to investment banks, so wouldn't they provide the retail investor a reasonable way to build wealth?

Also, I'm curious to know what you think of Warren Buffet's famously saying that retail investors should buy low-cost index funds. Clearly, he doesn't invest that way, but that's because he has the time and expertise to do better. Retail investors have neither.