Long term (10+ year) returns have historically been around 7%. Obviously that can vary quite a bit year-to-year.

Ask Jack Bogle... I'm sure he'll have a lesson or 5 for you.

If someone is unfamiliar with the return on index funds they are unlikely to know who Jack Bogle is or what his lessons are.

I got here: http://johncbogle.com/wordpress/

But I'm not sure where to go to find information about the returns.

That's John Bogle. You're looking for Jack Bogle. https://www.bogleheads.org/wiki/Bogleheads%C2%AE_investment_...

Apparently, they're the same person. https://www.bogleheads.org/wiki/John_Bogle

> John C. (Jack) Bogle, after whom the Bogleheads® are named, is founder of the Vanguard Group and creator of the world's first retail index mutual fund.

What's the lesson?

Index funds (over time) tend to beat most professional money managers, much less amateur speculators.

It's worse than that. Over any period of time index funds beat the average actively invested money because they have the exact same returns and less fees:

https://web.stanford.edu/~wfsharpe/art/active/active.htm

Less fees and transaction costs.

A historical returns of the stock market calculator: http://www.moneychimp.com/features/market_cagr.htm

Yes, index funds are less risky than undiversified individual assets but they can me much worse than boring.

Depending on the index you track, it can fall 80%. Consider the Asia ETFs in 2008, brutal.