Perhaps you are still being insufficiently cynical. Yes, index funds outperform managed funds, and investment professionals get rich off their fees and their media, not because they personally know how to beat the market.
But if I am to believe the analyses poured out daily at zerohedge.com, volume in the US stock market is now dominated by a few large institutional investors, looking for a place to put the free money they get by frontrunning the Fed's purchases of Treasuries, and this is a political choice: US federal debt is being monetized, and the US dollar debased, but since the bankers are all buying equities with their play money, the stock market is being driven up, which creates the illusion that growth is happening somewhere in the economy. :-)
I don't know how much of that is true, but my real point is that a revival of the financial crisis (this time because of sovereign debt rather than corporate debt) could put stocks into a zero-growth doldrum - of frequent crashes and long-term decline in value - for a decade or more. It's happened before, if it happens again then even index funds will be losing value, and it is precisely the sort of thing that would happen after the comprehensive discrediting of an overgrown and politically connected financial sector. People would go back to seeing stocks as a game of risk for the rich, rather than a happy place to put their retirement savings.
The result of making everyone an investor is that when everyone loses their money, they become a mob and burn the casino down, and run the people who were connected with it out of town. That hasn't happened in the US yet, but you can be sure that more than a few politicians are readying a line of populist nationalist outrage, for the day when the big banks become even more politically radioactive than they are now. Politics might even come down to who can mount the more convincing attack on the banks, the left or the right; and I would guess that the political red line will be the bankruptcy of cities and states.
You can already see the basic choice in Europe: Ireland, or Iceland. Ireland, so far, is agreeing to pay off the debts of its failed banks with taxpayer money, and the IMF has come in to supervise the process. Iceland's people said no way will we do that (even though they were happy to partake of the boom while it was still on), and had a small revolution in which they disowned responsibility for the actions, and the debts, of their financier class. It's part of how they ended up playing host to an entity as subversive as Wikileaks for a while.
So what I'm saying - what I'm predicting - is that you will see that same dilemma being faced at all levels in the US as the debt pyramid implodes, and in a country as big and diverse as the US, there will be cities and regions who take the radical option. Local politics will trump external economics, and they will disown or rewrite the agreements which would otherwise leave them in debt to outsiders for a generation. In some places, this will manifest as a reversion to the traditional local economy. In others, there might be some new thinking - green futurism or digital fabricators might be touted as the way forward. In such a turbulent context, even traditionally superior insights ("invest in index funds") may cease to apply, as the system undergoes a bigger change than most had imagined possible.
People who claim that the "dollar is being debased", don't know the basic facts. Inflation has actually been significantly lower than typical, the last couple of years. See for example http://investingforaliving.files.wordpress.com/2010/11/cpi-us-vs-japan.png
Market based inflation expectations (TIPS spreads) also indicate lower than typical expected inflation.
I am beginning to suspect that it is surprisingly common for intelligent, competent adults to somehow make it through the world for a few decades while missing some ordinary skill, like mailing a physical letter, folding a fitted sheet, depositing a check, or reading a bus schedule. Since these tasks are often presented atomically - or, worse, embedded implicitly into other instructions - and it is often possible to get around the need for them, this ignorance is not self-correcting. One can Google "how to deposit a check" and similar phrases, but the sorts of instructions that crop up are often misleading, rely on entangled and potentially similarly-deficient knowledge to be understandable, or are not so much instructions as they are tips and tricks and warnings for people who already know the basic procedure. Asking other people is more effective because they can respond to requests for clarification (and physically pointing at stuff is useful too), but embarrassing, since lacking these skills as an adult is stigmatized. (They are rarely even considered skills by people who have had them for a while.)
This seems like a bad situation. And - if I am correct and gaps like these are common - then it is something of a collective action problem to handle gap-filling without undue social drama. Supposedly, we're good at collective action problems, us rationalists, right? So I propose a thread for the purpose here, with the stipulation that all replies to gap announcements are to be constructive attempts at conveying the relevant procedural knowledge. No asking "how did you manage to be X years old without knowing that?" - if the gap-haver wishes to volunteer the information, that is fine, but asking is to be considered poor form.
(And yes, I have one. It's this: how in the world do people go about the supposedly atomic action of investing in the stock market? Here I am, sitting at my computer, and suppose I want a share of Apple - there isn't a button that says "Buy Our Stock" on their website. There goes my one idea. Where do I go and what do I do there?)