Legendary Vanguard Group founder Jack Bogle warns that there is an "awful lot" to fear in the current stock market and investors have few “good options.”

"This is a hard time to invest because there aren't a lot of good options to stocks, and bond yields are extremely low," he told CNBC.

He said the Federal Reserve’s continued insistence on low interest rates has only artificially boosted stock prices.

"That's a scary thing because it can't stay that way forever," he said. "So, I do advocate a cautious approach to investing."

"I've been through, I think, four 50 percent declines, at least three, and we get over them and march on," he said. "It's a good idea to not pay too much attention to the stock market and think about the long-term productivity of business," he said.

"You've got to keep investing in stocks and bonds, because I don't think the other alternatives — commodities, for example, or gold — have any long-term return prospects at all," he said.

To be sure, Bogle isn’t the only prominent economic expert to paint a bleak future of the market.

Nobel Laureate Economist Robert Shiller says that the world’s economy remains mired in “a vicious circle of despair” seven years after the 2008 global financial crisis.

“Fear causes individuals to restrain their spending and firms to withhold investments; as a result, the economy weakens, confirming their fear and leading them to restrain spending further,” wrote Shiller, a Sterling Professor of Economics at Yale University and is a fellow at the Yale School of Management's International Center for Finance.

“The downturn deepens, and a vicious circle of despair takes hold. Though the 2008 financial crisis has passed, we remain stuck in the emotional cycle that it set in motion,” he wrote in his Project Syndicate blog.

“It is a bit like stage fright. Dwelling on performance anxiety may cause hesitation or a loss of inspiration. As fear turns into fact, the anxiety worsens – and so does the performance. Once such a cycle starts, it can be very difficult to stop.”

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