According to the latest financial security index by Bankrate.com, here’s how Americans prefer to invest money that they don’t need for more than 10 years:

26% say they prefer cash for long-term investments.  Cash is arguably a great place to store your wealth briefly, however 80 years of data show cash is a horrible long-term investment. 

The following chart shows that cash has averaged a negative real, after-tax return (be sure to click on the chart for a closer look).  Inflation and taxes are killers.

Click to enlarge

“Americans not saving enough is well-documented, but hunkering down in cash investments and settling for low returns will only magnify the problem of not having a sufficient nest egg to meet longer-range financial goals such as retirement,” said Greg McBride, CFA, Bankrate.com’s senior financial analyst. “Other choices may not do the trick either, as real estate is not only very cash-intensive, but often illiquid. And precious metals spit out zero cash flows, with gains solely dependent on price appreciation.”
Sources:
BankRate.com