[robby]

I think the numbers show that some luck is involved. If you by chance happened to start your 30 years of investing on 2003 rather than 2000, your money would be worth much more. I've been reading and it seems that the first 5 years and the last 5 years are crucially important.

You also mentioned the need to diversify. Isn't what you happen to diversify into luck? If you happen to hit the right spot, then you win and if you don't, you can lose big. I think it's very misleading when people throw out the 10% average because if your % gains are negative for the first five years and the last five years, you aren't going to be anywhere near $1 million.