Investing over the long term in index funds?

The Market According to GARP says:

The experts say this is a stock picker’s market. By that they mean the market could move sideways for some time, and offer its biggest rewards to those investors who know how to select good stocks.

I definitely believe that we’re going into a sideways market. Even the term “sideways” makes things sound somewhat pleasant. Stocks will move down, then up, then down, then up until we finally reach the “hey things have moved sideways” point. With that setup, the article goes on to say:

Reams of research show that long-term investors who keep their money on autopilot in low-cost index funds will beat most stockpickers and market timers over the long haul.

I think there’s a disconnect here. A “sideways” market, by definition, produces no return. Rather than going up or down, it just goes sideways. So, for the next few years, those index funds will go up and down, ultimately producing no return at all. I, for one, don’t plan to let my money sit around in stocks earning 0% for several years, when I could just move it into a money market account to earn something. Series I US Savings Bonds are very nice as well.

I’m content, though, with large groups continuing to leave their money in indexes. It just provides less competition for other investments…