Remember the "Millionaire Next Door"? He was that thrifty dry cleaner or welder who drove an old pickup truck, wore a Timex and bought suits off the rack (if he bought them at all). He scrimped, saved and invested his way to $1 million. It was a quaint portrait—and a great book in the 1990s. But by the 2000s, the giant green tide of megawealth, filled with super-earners and super-spenders, transformed the world of millionaires. Saving your way to $1 million was still possible, but it wasn't considered wealthy. Now a new study suggests that the concept of the "Millionaire Next Door" may be coming back in vogue—at least psychologically. A study from PNC Wealth Management asked people worth $5 million or more in investible assets about the "actions that have most contributed to their financial success."

(Read more: Can you be addicted to wealth?)

The No. 1 response? It wasn't income. It was "saving early and regularly." The second most common response was "making smart investment choices." In a distant third was "earning a lot of money." Ranked fourth was "controlling spending." When asked to rank the greatest influences on their success, 63 percent said "hard work." That was followed by "good decisions" (16 percent). Only 9 percent said "luck" was the top influence on their success. (Read more: How the world's rich give away their millions) "Most of the millionaires surveyed have controlled their own destiny by working hard and saving early and regularly," said Joseph Jennings, director of investments for PNC Wealth Management. "These are personal choices over which we all have control. This indicates that the 'American dream' is still very much alive." Of course, every survey done by a financial institution should be taken with a grain of salt. Wealth management firms tend to promote the image of hard-working, heavy savers and investors among their clients. And clients sometimes say the right things in surveys, but act very differently in reality. As the author Michael Lewis said in his now famous Princeton commencement speech, "if you have had success, you have also had luck—and with luck comes obligation."

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