When it comes to long-term investing, putting that money to work for you for 10 years or more, a lot of people still prefer cash, according to a new study by Bankrate.com.

And that concerns Greg McBride, chief financial analyst at Bankrate.

"Cash is a miserable long-term investment," McBride told me. "You don't grow your buying power; you only see that buying power eroded. Cash is great for that emergency savings - that's what it's there for - but it's not good for long-term investments."

McBride is also troubled about how few Americans - only 17 percent, according to this survey - prefer the stock market for long-term investing.

He says people who avoid the market because they're afraid to take any risk, may be in for a big surprise when it comes time to retire.

"Most people don't save enough to where they can afford to hunker down in safe-haven investments and still get to what they need in the future," McBride said.

His message to investors: When you use the stock market for long-term investing you don't have to worry that much about short-term volatility.