75% of employees aren't taking a crucial step to get rich

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According to self-made millionaires, if you want to make big money, you can't be content with only one source of revenue. You have to go for more.

"You won't get rich without multiple flows of income," says Grant Cardone, who was deep in debt before reaching seven-figure status.

Research backs his claim. As author Thomas C. Corley found in his five-year study of self-made millionaires, the rich "do not rely on one singular source of income," he writes in "Change Your Habits, Change Your Life."

"Sixty-five percent had at least three streams of income that they created prior to making their first million dollars," Corley says, such as real-estate rentals, a side hustle or a part-time job.

Yet, according to new research from recruiting software company Jobvite, only a quarter of employees have a second source of income outside of their primary job.

Relying on one form of income could be costing middle-class workers. After all, what sets the rich apart from the rest is their focus on earning, says self-made millionaire Steve Siebold.

"The masses are so focused on clipping coupons and living frugally they miss major opportunities," he writes in "How Rich People Think." "Even in the midst of a cash flow crisis, the rich reject the nickel-and-dime thinking of the masses. They are the masters of focusing their mental energy where it belongs: on the big money."

There's no need to completely disregard smart saving strategies. But if you want to reach seven figures, "stop worrying about running out of money and focus on how to make more," Siebold says.

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Simple steps to get rich from a self-made millionaire
Simple steps to get rich from a self-made millionaire