Billionaire John Paul DeJoria started wearing his signature all-black to save money early in his career

Born into a poor immigrant household, John Paul DeJoria had very little from day one.

Before building Patrón tequila and John Paul Mitchell Systems hair products - which led to an estimated $3.1 billion fortune - DeJoria had to get creative to stay afloat.

He lived out of his car and even resorted to collecting discarded bottles to cash in at grocery stores.

He also chose to wear all black, strictly for financial reasons: stains hide well, which cut his dry cleaning bill, he told Farnoosh Torabi on her new CNBC show, "Follow the Leader."

While the billionaire has no problem covering a laundry bill today, the habit stuck.

He consistently wears black pants, a black shirt, and a black blazer, but today, his wardrobe offers more than a financial benefit. As Torabi explains, "Wearing repeat outfits means he can spend less time and thought worrying about what to wear. Instead he can apply those resources to more important things like family and business."

DeJoria isn't the only one to stick to a "uniform" to expend less mental energy on mundane decisions - or, to avoid what psychologist call decision fatigue.

There's Mark Zuckerberg and his signature gray tee-shirt - and Barack Obama and his blue or gray suit.

As Obama told Vanity Fair in 2012, "You'll see I wear only gray or blue suits. I'm trying to pare down decisions. I don't want to make decisions about what I'm eating or wearing. Because I have too many other decisions to make."

Zuckerberg said a similar thing during a public Q&A session: "I really want to clear my life to make it so that I have to make as few decisions as possible about anything except how to best serve this community ... I feel like I'm not doing my job if I spend any of my energy on things that are silly or frivolous about my life."

And then there's the woman who took it a step farther and has worn the same outfit to work every single day for the past several years. As she told Business Insider, "I just wanted to save some time and energy."