Kevin O'Leary has invested hundreds of thousands of dollars in small businesses over the course of his tenure as a star and investor on ABC's "Shark Tank."
But there is one business to which he refuses to fork over his hard-earned dollars: coffee shops.
"Do I pay $2.50 for a coffee? Never, never, never do I do that," O'Leary tells CNBC Make It. "That is such a waste of money for something that costs 20 cents. I never buy a frape-latte-blah-blah-blah-woof-woof-woof for $2.50." Instead, he makes it at home.
"I drink coffee, one cup every morning," he explains. "It costs about 18 cents to make it, and I invest the rest." (That probably means he's not a fan of $7 avocado toast either.)
That idea — saving small sums and investing continually — is central to O'Leary's personal finance advice.
"The truth is, there is a lot of crap you don't need," he explains. "What I've learned to do, and what has really helped me in maintaining growth in my own personal investing is, anytime I pick up something I'm going to buy, I say to myself, 'Do I really need this?'
"Because if I don't buy it, the money is going to be invested and make money every year for me while I'm sleeping."
He suggests you follow suit. No matter how much your income is, "You have to take 10 percent of your paycheck every two weeks and invest it," O'Leary advises. "People say, 'I can't afford that! I can barely afford my rent!' But it's not true, you buy crap you don't need every day."
For O'Leary, that coffee just isn't worth it.
"I don't buy a lot of crap. I buy good stuff that I need, and I invest the rest, and it works," he says. "Try it sometime."
Video by Andrea Kramar
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Disclaimer: CNBC owns the exclusive off-network cable rights to "Shark Tank."