A couple comments;
First, someone stated they didn't know anyone who solely invested in the S&P500 Index. What's a guys SUPPOSED to invest in and more importantly HOW is a guy supposed to know what to invest in? Remember, these are pre-early retirement guys. Guys who are working their butts off to make enough money to sock away so they can retire early. There's usually a family and a home to take up what ever time they aren't working. There's not much time to spend tracking funds, bonds, high caps, growths, etc. So, why wouldn't the common worker consider putting his savings into an index fund? I've tried both ways and I'm no more better off guessing what funds to invest in than the S&P500 index and it's the rare exception it seems to find someone on here that does consistently better either.
Second; Someone said 7 years isn't a long term. It sure is long term if you are trying to retire early. If you started to work and save at 21 and wanted to retire around 42 (that's early retirement, right?) then 7 years is one third of your investing time before you need to really get conservative and count on this nest egg as income. Even if you planned to work another 7 years; to 47, or even seven years after that; to 54, then 7 years is still a long time; 20 or 25% of the investment growth stage of your savings.
My advice to investment is this; Take on no debt of any kind, pay off your home before you think you'll be able to retire, consider real estate rental for part of your retirement income, save enough money and plan that the most you are going to be able to do is slow down the ravages of inflation. You need to save faster and with more money than inflation will eat away at the savings because the growth in the market isn't going to keep up with inflation AND grow your savings at the same time. Not in the long run, whether that's 7 years or 7 times 7 years. The risk is too great and will catch up sooner or later. The only possible exception is the guy who somehow has figured out the investment world well enough he could probably make his living at advising. That isn't the normal guy who's saving, working and raising a family. It takes too much time each day to understand the market.